LIBRARY, A & M COLLEGE, CAm§ug E-131-6M-L180 T/FLXAS AfiRlCULTURAL EXPERIMENI - \TION A. B. CONNER. IHRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS BULLETIN NO. 510 SEPTEMBER, 1935 p DIVISION OF RURAL HOME RESEARCH Seasonal Variations of Growth in Weight and Height of Texas Sehool Children \ u ' .‘ .~ v w ' ' -' - | , qrfafl- .' - T $211k Q4‘. ._~~ v I ‘H ' - - - . . - ~- / L i B R A R Y lerinzaihual & Mechanicai CHI-IRE? h’ T"?! Iivyfia AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President STATION STAFF? Administration : A. B. Conner, M. S., Director R. E. Karper, M. S., Vice Director Clarice Mixson, B. A., Secretary M. P. Holleman, Chief Clerk D. R. McDonald, Asst. Chief Clerk Chester Higgs, Executive Assistant Howard Berry, B. S., Technical Asst. Chemistry: G. S. Fraps, Ph. D., Chief; State Chemist S. E. Asbury, M. S., Chemist J. F. Fudge, Ph. D., Chemist E. C. Carlyle, M. S., Asst. Chemist T. L. Ogier, B. S., Asst. Chemist A. J. Sterges, M. S., Asst. Chemist Ray Treichler, M. S., Asst. Chemist W. H. Walker, Asst. Chemist Velma Graham, Asst. Chemist Jeanne F. DeMottier, Asst. Chemist W. H. Garman, M. S., Asst Chemist A. R. Kemmerer, Ph. D., Asst. Chemist A. W. Walde. Ph.D., Asst. Chemist F. J. McClure, Ph. D., Asst. Chemist Horticulture: S. H. Yarnell, Sc. D., Chief Range Animal Husbandry: J. M. Jones, A. M. Chief B. L. Warwick, Ph. D., Breeding Investiga. S. P. Davis, Wool and Mohair Specialist J. H. Jones, B. S., Animal Husbandman Entomology: - F. L. Thomas, Ph. D., Chief: State Entomologist H. J. Reinhard, B. S., Entomologist R. K. Fletcher, Ph. D., Entomologist W. L. Owen, Jr., M. S., Entomologist J. N. Roney, M. S., Entomologist J. C. Gaines, Jr., M. S., Entomologist S. E. Jones, M. S., Entomologist F. F. Bibby, B. S., Entomologist "R. W. Moreland, B. S., Asst. Entomologist C. E. Heard, B. S., Chief Inspector C. J. Burgin, B. S., Foulbrood Inspector Agronomy: E. B. Reynolds, Ph. D., Chief R. E. Karper, M. S., Agronomist P. C. Mangelsdorf, Sc. D., Agronomist D. T. Killough, M. S., Agronomist J. O. Beasley, M. S., Asst. Agronomist Publications: A. D. Jackson, Chief Veterinary Science: ‘M. Francis, D. V. M., Chief H. Schmidt, D. V. M., Veterinarian "F. P. Mathews, D. V. M., M. S., Veterinarian Plant Pathology and Physiology: J. J. Taubenhaus, Ph. D., Chief W. N. Ezekiel, Ph. D., Plant Pathologist L. B. Loring, M. S., Asst. Plant Pathologist G. E..Altstatt, M. S., Asst. Plant Pathologist “Glenn Boyd, B. S., Asst. Plant Pathologist Farm and Ranch Economics: L. P. Gabbard, M. S., Chief W. E. Paulson, Ph. D., Marketing C. A. Bonnen, M. S., Farm Management t"W. R. Nisbet, B. S., Ranch Management "A. C. Magee, M. S., Farm Management Rural Home Research: Jessie Whitacre, Ph. D., Chief Mary Anna Grimes, M. S., Textiles Sylvia Cover, Ph. D., Foods i Soil Survey: "W. T. Carter, B. S., Chief E. H. Templin, B. S., Soil Surveyor J. W. Huckabee, B. S., Soil Surveyor I. C. Mowery, B. S., Soil Surveyor Botany: V. L. Cory, M. S., Acting Chief Swine Husbandry: Fred Hale, M. S., Chief Dairy Husbandry: O. C. Copeland, M. S., Dairy Husbandman Poultry Husbandry: R. M. Sherwood, M. S., Chief J. R. Couch, M. S., Assoc. Poultry Husb. Paul D. Sturkie, B. S., Asst. Poultry Hush. Agricultural Engineering: H. P. Smith, M. S., Chief M in Station Farm: .T. McNess, Superintendent Apiculture (San Antonio): H. B. Parks, B. S., Chief A. H. Alex, B. S., Queen Breeder Feed Control Service: F. D. Fuller, M. S., Chief James Sullivan, Asst. Chief. D. Pearce, Secretary H. Rogers, Feed Inspector L. Kirkland, B. S., Feed Inspector D. Reynolds, Jr., Feed Inspector A. Moore, Feed Inspector J. Wilson, B. S., Feed Inspector G. Wickes, D. V. M., Feed Inspector J. K. Francklow, Feed Inspector assess? SUBSTATIONS No. 1, Beeville, Bee County: R. A. Hall, B. S., Superintendent _ No. 2, Tyler, Smith County: P. R. Johnson, M. S., Superintendent No. 9. Balmorhea. Reeves County: J. J. Bayles, B. S Superintendent No. 10, College Station. Brazos County: R. M. Sherwood, M. S., In Charge "B. H. I-Iendrickson, B. S., Sci. in Soil Erosion L. J. McCall, Farm Superintendent "R. W. Baird, M. S., Assoc. Agr. Engineer No. 3, Angleton, Brazoria County: R. H. Stansel, M. S., Superintendent H. M. Reed, B. S., Horticulturist No. 4, Jefferson County: R. H. Wyche, B. S., Superintendent "H. M. Beachell, B. S., Junior Agronomist No. 5, Temple, Bell County: Henry Dunlavy, M. S., Superintendent C. H. Rogers, Ph, D., Plant Pathologist H. E. Rea, B. S., Agronomist "E. B. Deeter, B. S., Soil Erosion No. 11, Nacogdoches, Nacogdoches County: H. F. Morris, M. S. Superintendent “No. 12, Chillicothe, Hardeman County: "J. R. Quinby, M. S. Superintendent "J. C. Stephens, M. A., Asst. Agronomist No. 14, Sonora, Sutton-Edwards Counties: W. H. Dameron, B. S., Superintendent I. B. Boughton, D. V. M., Veterinarian W. T. Hardy, D. V. M., Veterinarian O. L. Carpenter, Shepherd "O. G. Babcock, B. S., Asst. Entomologist No. 15, Weslaco, Hidalgo County: "P. L. Hopkins, B. S., Jllniorrcivii Engineer W, H, Friend, B, S., Superintendent No. 6 Denton, Denton County: P. B. Dunkle, M. S., Superintendent "I. M. Atkins, B. S., Junior Agronomist No. 7. Spur, Dickens County: R. E. Dickson, B. S., Superintendent B. C. Langley, M. S., Agronomist No. 8, Lubbock, Lubbock County: D. L. Jones, Superintendent Frank Gaines. Irrig. and Forest Nurs. Members of Teaching Staff Carrying G. W. Adriance, Ph. D., Horticulture S. W. Bilsing, Ph. D., Entomology D. Sooates, A. E., Agricultural Engineering A. K. Mackey, M. S., Animal Husbandry R. G. Reeves, Ph. D., Biology J. 8. Mogford, M. 8., Agronomy F‘. R. Brison. M. S., Horticulture ‘Dean, School of Veterinary Medicine. S. W. Clark, B. S., Entomologist W. J. Bach, M. S., Plant Pathologist J. F. Wood. B. S., Horticulturist No. 16, Iowa Park, Wichita County: C. H. McDowell, B. S., Superintendent L. E. Brooks, B. S., Horticulturist No. 19, Winterhaven, Dimmit County: E. Mortensen, B. S., Superintendent “L. R. Hawthorn, M. S., Horticulturist Cooperative Projects on the Station: W. R. Horlacher, Ph. D., Genetics H. Knox, M. S., Animal Husbandry A L. Darnell, M. A., Dairy Husbandry ‘R. O. Berry, B. S., Biology R. T. Stewart, Ph.D., Agronomy V A. Little, M. S., Entomology TAs of September 1, 1985 "In cooperation with U. S. Department of Agriculture. flu cooperation with Texas Extension Service. ‘In cooperation with State Department of Agriculture. This bulletin reports the seasonal variation of growth in weight and height found among white, Mexican, and negro school children in Texas. It is based upon the records of periodic measurements of approximately 1000 pupils over a period of two and one-half school years. The average of yearly net gains in weight was 71/; pounds for white children, and 81/; pounds for both Mexican and negro, groups. This small race difference is probably due to a slightly larger proportion of older children in the Mexican and negro groups than in the white. The average yearly gain in standing height was about 2 inches, and in sitting height about 1 inch for all races. Fall was found to be in general the best; season for gains in weight by" all three races. The relative gains of spring and summer were not consis- tent between any two of the three races. The summer gains of white children were the lowest of the three races, and those of the negroes the highest; but differences between the races were small. The variation between the three races in seasonal gains suggests that some other factor (or factors) may have a greater influence upon gaining weight than does any natural tendency to gain consistently more in one season than another. The ratio or gainers to losers was higher", in fall than in spring months for all races. An average of approximately three times as many white and Mexican children gained each, month of the school year as lost, while only twice as many negroes gained as lost. The subgroups of each race according to sex, age, birth-month, type of body-build, and certain living conditions, showed essentially the same seasonal variation as did the whole race group. Therefore none of those factors influenced seasonal variation. October was always a month of excellent growth in weight, the average net gains of the three races ranging from 11.3 per cent to 16.1 per cent of the yearly gains. April was outstanding for poor gains, no more than from 1.4 per cent to 6.4 per cent of the yearly net gains having been made in this month. No explanation of the excellent gains in October or of the poor gains in April was found in the records of food eaten; nor in the relation of minor illnesses, especially colds, to weight changes; nor in climatic condi- tions as indicated by records of the U. S. Weather Bureau in San Antonio. The records of 98 children who at no time showed a loss in weight were examined individually. About two-thirds of them agreed with the trends shown by the average net gains of all the children in that the rate of growth in fall was greater than in either spring or summer. The other one-third had a higher rate of gain in either spring or summer than in fall, showing that good gains can be and often are made in these seasons. This empha- sizes the importance of considering each child individually in his course of growth. A child’s failure to gain should not be attributed complacently to the season of the year. Too much departure from regularity of gain calls for special attention, althoughthe degree of uniformity to be expected in normal growth must be determined by further study. Average monthly gains in standing and sitting heights for the three races showed negligible differences between spring-to-fall and fall-to-spring periods. In contrast, weight gains over the same periods were consistently greater in fall-to-spring than in spring-to-fall periods. Apparently the growth in height of these school children was fairly uniform throughout the year, although there may have been marked differences in rate within shorter time intervals than those used in this study. CONTENTS Introduction 5 Plan of Study ..... __ 5 Place and Time of Collecting Data 5 Type of Data._ 6 Methods of Collecting Data 6 Growth in Weight _. 10 Selection of Records i . 110 Seasonal Variation of Growth in Weight within Groups According to: Race . . . _ _ . _ . _ _ _ . . _ . . _ . _ _ . . _ . . _ . _ _ . . . _ _ _ . 114 Average Net Gains Derived from Group Weights ........................... --14 Individual Monthly ‘Weight Changes 19 Sex 24 Age 27 Month of Birth ______ .. 34 Type of Body-build ....... _- 36 Living Conditions 38 Constancy of Gain ........ -- 41 ~ As a Group _______ "41 As Individuals 43 Diet . . _ . _ _ , C _ S _ . . . . . . . . i _ _ C . _ . . S _. 56 Minor Illnesses > 57 Climatic Conditions ..... __ r59 Other Possible Factors r62 Growth in Height 62 Selection of Records .......................................................................... -1_ ........ __62 Seasonal Variation, by Race and Sex ______________________________________________________ -- 63 Group A, Having Gain of 2 Years A 63 Group B, Having Gain of 1 Yearmm, 65 Age Groups - M67 Acknowledgments ____ __ 69 Summary and Conclusions iiiii -i \ 69 Literature Cited ...... .. 71 BULLETIN NO. 510 SEPTEMBER, 1935 SEASONAL VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF TEXAS SCHOOL Cl-IILDREN* J nssu: Wmucnn Since the pioneer studies of Bowditch (3) upon the growth of children in Boston public and private schools in 1875-6, interest in growth as an expression of physical well-being has become more widespread until today a health program including some physical measurements of the pupils is a part of most school curricula. The vast amount of attention given more re- cently to the question of growth was indicated by Scammon (21) who reported to the White House Conference on Child Health and Protection that in the lastdecade there had ‘appeared over 2000 separate publications per- taining to growth and physique of the child. In this same session of the Conference, Wilson (27) emphasized the necessity of having consecutive measures of growth at successive ages of the same children. Relatively little of the vast accumulation of data on growth is of this individualized kind. Most studies have been of the generalized type wherein a single measurement is made on each member of a large group, and averages are then derived from these single measurements. One of the questions relating to the usual course of growth in weight and height, upon which available evidence is conflicting, is that of seasonal variation in the rate of growth. Among studies in which seasonal differ- ences have been found in increments to weight and height (5, 6, 7, 9, 10, 11, 13, 16, 18, 19, 25) there is disagreement as to the season of maxi- mum and minimum gains. There is only a meager fund of information respecting the influence of race upon growth processes. This study, of the individualized ty-pe, was undertaken with the hope of making a con- tribution toward answering the questions as to whether seasonal varia- tion occurs in the rate of weight and height increases of school-age children, and whether characteristic and distinctive differences in seasonal rates of growth exist among three race groupsL-Mexican, white, and negro -—living in the same locality in Texas. PLAN OF STUDY Place and Time of Collecting Data The cooperation of three public schools in San Antonio was secured. These schools were selected by the elementary supervisors as“ representa- tive of the three races. Collection of data began in January 1929 and was completed in May 1931. Approximately 500 pupils in each of the three schools participated in this study each school year. Except for the last school year, when no first grade pupils were included in this study, ‘Submitted for publication February 12, 1935. TThe children included in this study, all citizens of the United States, have been classi- fied into three groups, Mexican, other whites, and negroes. As a matter of con- venience these grouns are referred to as race groups, and for the sake of brevity in this bulletin the designation “white” is used for the second of these groups. .6 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION all of the children in the White and negro schools were weighed and measured. In so far as feasible, the same children in the Mexican school were retained in the study during the period of data collection. The white and Mexican children were distributed through the first five grades (ele- mentary school of Texas) and the negroes through the first eight grades (elementary and junior high schools of Texas). Owing to the promotion of some pupils to junior high school and the to the entrance of new pupils in the second year of the study, the total numbers of children appearing in the records were 781, 830, and 981 for negro, Mexican, and white groups, respectively. Type of Data The physical measurements of each child were weight, standing height, sitting height, width of hips, and width of shoulders. Other data secured and used for this report include (1) birth date, from which age was calculated; (2) the child’s report on each weighing date of any illness since his preceding weighing; (3) a written record of all food eaten by each child for from two to four days within the time of the monthly weighing period in the first one and one-half years of the study, and a similar record confined to third grade children in a fall, a winter, and a spring month of the last year; (4) indications of living conditions-—number of adults and of children in the family, total number of rooms in the house, and number of bedrooms and bath rooms—as reported by each child the last year of the study; and (5) a monthly and annual meteorological summary secured from the U. S. Weather Bureau in San Antonio for each month and year covered by this study. Methods of Collecting Data Data were collected only during thegschool year. The detailed schedule of periods within which measurements were made of weight and height, with the intervals between first days of consecutive periods, is given in Table 1. The monthly measuring periods in each school came at ap- proximately the same time of the month. The interval between weighing periods averaged about 30 days. The short November interval in 1929, about three weeks in all schools, should be noted. The longest interval, 42 days (October 1929), and the shortest, 20 days (November 1929), were in the white school. Ideally the weighing intervals should have been per- fectly uniform, but such achievement was not practicable since this work was being made to fit into the regular school program. As pointed out later, the variation in the length of intervals appears not to vitiate the conclusions which may be drawn from this study. Height was measured once each semester (or five times within the period of data collection). " The width of hips and of shoulders was determined once for each of the children and twice for some of them. The purpose of securing data that would contribute to our more accurate knowledge of the laws of growth influenced the selection of equipment VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 602.202" M€m3o=om 02$ mo haw umnmw op womnon 02o mo haw umnmm 59G 000550» . N3 v-H 5&2 dmém 594w Mm $42“ mm HNAWH hag om TH 5&2 6.1mm 1&4 52 wmaom MQ< N5 5-2 5&4 mm £45 .2224 mm >7»? .34 5 N; Q94 .345 26E T. P». 5-m~ 0N2 mu M242 .202 mm w-» v82 % 5 $4.2 ..Qwrfl mm 3-3 50h mu mum £01m T. w” 5-3 SNH mm 3&2 Afiwh. mm 2.1m Jfiwfi l] mw wnvwwfi %w .242 dwQ 5 m; dwQ - . m 2-2 <62 3 Z. .52 5N 3-2m 50C 2m 3-2 50C 3N w; 60C 520m 03m 5 wNQN 50D mu QNA: doO S: w; 60C 6m$~ $90M £2 wméw 03m $2 £42 JQQW T. 6 MM wmw “Mm a 22-2 m: a fi hw.“ m. - . 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Boson @033 125$ c.2002 200:3 c8165 3on3 3E3 1 029mm E23 200300.- .326 we manna: via 22.»? 2512. ufinnmuoi we Suva-Gm t» Sana. 8 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION and techniques and led to the adoption of certain precautions in the routine procedure. For Weighing, Continental scales of platform type calibrated in ounces were used. A scale was provided for each school. These scales were checked against each other at the outset, and periodically within the time " f _ 0.5 Flfiidali Ranxds»; , ; Q Tqits gnu/same Kxpoxiazyzai .'2§§a%$§m Calizze 810%)» 7mm. Fig. 1. Typical set-up for a measuring period in the weighing room at the Mexican school. The observer at the weighing scale recorded all measurements-——weight, standing height, and sitting height. The assistant, at the right, brought the pupils from the class room, assisted them in donning the weighing garments, and organized the line of children. Weighing agrments, after use, were put into the laundry bag on the chair back at the right. of data collection. Their accuracy was tested at intervals by the San Antonio sealer of weights and measures. To make it possible to determine the nude body weight, Weighing gar- ments were worn during the weighing period. The younger boys and all the girls Wore unbleached muslin robes made especially for the purpose, and the boys in the fourth grade and above Wore regulation gymnasium suits of knitted shirts and cotton twill pants. These garments were laundered after each use and were _ checked at intervals for loss in weight. As each child was weighed, his Weight was entered on his record card; the scale was read again and the record checked before the child stepped off the scale platform. The known weight of the weighing garment was subtracted from the weight of the child and the garment, to give the nude weight. g Standing and sitting heights were measured with the Baldwin measuring tape fastened with one-inch adhesive to a specially constructed board. This VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 9 board was fastened rigidly in a perpendicular position to the bench specially constructed foruse in measuring sitting height. The technique of Baldwin (1)'as modified by Roberts (20) was used for standing height. For sitting height (stem length), Roberts’ (20) description of procedure was followed. A set of the equipment for measuring height was provided for each school. Metal calipers from the Smithsonian Institution were used for measuring width of shoulders and of hips, according to Baldwin’s technique demon- strated to the author by a member of Dr. Baldwin’s staff in the Iowa Fig. 2. Typical set-up for a measuring period in the white school. The observer at the weighing scale recorded all measurements——weight, width of shoulders, and width of hips. The assistant is questioning the pupils concerning their living conditions. Gymnzsium suits were the weighing garments worn by boys in the third grade and a ove. ‘ Child Welfare Research Station. Two observations each of standing and sitting heights and of width of hips and of shoulders were made upon each child. If these agreed, the result was recorded; if not, the measurement was repeated until satisfactory results were obtained. With the exception of one period in the negro school when the weighing was done by the assistant, all measurements were made by the project F ~ leaders. Two observers worked together in those periods when more than f one measurement was made, the observer who Weighed the children doing all the recording. Between measuring periods the weighing scale and the equipment for measuring height were left in locked cases at the school. » ., The time of day for measuring any group of children was kept as nearly uniform throughout the two and one-half school years as was concordant 10 BULLETIN NO. I510, TEXAS AGRICULTURAL EXPERIMENT STATION with the promotion of the children through the grades and the convenience of the teachers. Throughout each semester each class, the girls in one group, the boys in another, was brought to the weighing room in the same quarter of the school day. As the children went from their class- room to the weighing room, they were not permitted to drink at the fountain and they were sent to the toilet room to empty the urinary bladder. The extent to which the variable weight of the child’s clothing, change in the time of day for weighing (afternoon to morning, or vice versa), and failure tocmpty the urinary bladder may effect the accuracy in determining monthly weight changes has been previously reported (22). These precautions are indispensable to accuracy. Figures 1 and 2 show the weighing garments, the general lineup of a group of children in the weighing room, the equipment as it was set up for use, and selected steps in the technique of some of the measure- ments. GROWTH IN WEIGHT Selection of Records The data upon weight have been examined from two approaches, (1) the performance of groups selected according to several different bases of classification within each race, and (2) the performance of a number of individuals in each race whose records were considered separately as well as in a group. The number of children weighed each month varied, (1) because of changes in school population due to promotion out of the elementary grades and to entry of new pupils, (2) because of absences, and (3) because all weights were discarded that were less than the preceding in a given record When the loss in weight was associated with a major illness such as measles or influenza. If the child's weight was the same at two consecu- tive Weighings or showed a gain despite his having suffered the illness, the weight was regarded as a valid one. The results of preliminary analyses using the record of every child regardless of how often he was weighed, guided in selecting and handling data used for the present purpose. In a comparison of the mean weight- of 42 each of morning-Weighed and afternoon-weighed groups (10 white children, 16 Mexican, and 16 negro) selected by age to nearest birthday, only four were found in which there was a statistically significant dif- ference, being respectively 4.48, 4.16, 4.04 and 4.30 times the probable error of the difference. Because of this preponderance of insignificant dif- ferences between mean weights of morning-weighed and afternoon-Weighed groups, and because of other factors (such as variation in the weight of food eaten in the meals preceding the weighing, of liquids drunk, and of defecation) that had an influence, it was concluded to use morning and afternoon weights together in dealing with group values. The varying number of records in the several months was found unsuitable for the determination of seasonal variations. It became evident that the age of every child must be calculated from a fixed point in the calendar (January 11 VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN m2 $2 2 m Hm H m2 mm mm m2 H»? 5H mm m 2 H 3 Hm mm 95 nHbU 0.502 H: 3 m HH o mm 5 3 N3 wSm 22 2 ww HH 2 o Em 30H m2 8 3w mm om w w a m“. 2. mm Q3 2&0 cwoHxwE mm 2 m m o HH. mm m» 22 2am _ 3H fi. 3 2 om .~ H2 _ 22 m» E ma . S. 2 3 0 w 2 _ 2. 2 3 N3 n30 “s23 m2 .3“ H. 3 H _ B. S S 2m 93M 3:0 E20 9.2 3.00 30o ommH m .580 4 .596 5.2. 32 22 % a 22 32 ~22 a 22 $8: m 8 2 130E 00252005 . Emmi H25 _m~flm$~m~w0flcw~mu NW mfiflmwvflflw-Hmwmm» N 050.10 O Q5020 mH Q5050 < Q5020 005B Hm 0H H T30 H0 X 05am =3 THQH. Ho X 05mm :3 was“; 02000.2 fen no 0:0 .23» 0.20002 230s no one 8.58129,» Now 000M 00.25235 00.52232 £95.23 wwuuoowu mwoH 0: s3? £96.23 0022500 H0208» M02903 3E0 .632 miwwm HQMHQJ 20h 25am “EMF? norm dZ :33. PHOQQH m3» 5m 8W5 200502 SHE? mi: Gm Nimufifimflmfihfifi QOHQZGO HO HUfiEn-z -N Qwfiflhw 12 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION 1 was used) so as to hold each individual in a given age group through one 12-month cycle. * It was therefore decided to limit the records used to those in which the seriesof 9 weighings was unbroken through a period covering 12 con- secutive calendar months. These were chosen to give the largest pos- sible number of such records secured during the collection of data. The O as wan: CHILDREN I/ \ no. 01-" CASES / \\ anon? ALL 501s arms °-—-/ ~ ~-— mm 981 s19 462 E20 I 0/ \°\\ . a ,2. o w-wcourmm mono s24 111 141 G 1s l ° \ == I g \ n10 \ => \ 2 ' 1 - s °' \ E I \ a‘ o’ \°\ 0 n _§OE‘ _ m: s s 1 a 9 1o 11 12 1s 14 1s 1s 11 1s 19101: 2s f\“~o 2o rmncm 0111mm // \ NO- OF CASES E /' \ f3 V‘ \\ 111.1. sows onus F‘ 51s o‘ sso 421 40s g 211 13s 144 31o \\, 5 ’ \ / °\ E s n. of/ \\ o‘. o ° \.___,,\.__ - ms s s '1 a s 1o 11 12 1s 14 1s 1s 11 1a 1910s 21s umno cnnmmn N0. 0F QASES 0-4 /°\ 3 I ALL sors GIRLS gm 131 ssz ass g 29a 144 1s4 =5 s1 E \ , g \°\ m 0_B. --<> ‘ 1oz s e '1 s 9 1o 11 12 1s 14 1s 1s 1'1 1e 191cm Fig. 3. Distribution- of the total number of children weighed from 1 to 21 times within the period of data collection, and of the number who had “complete records” of weighing through one or both record years. first such period extended from February 1929 through January 1930, and in this bulletin is called the “record year” of 1929; the “record year” of 1930 extended from February 1930 through January 1931. Each of these periods covered the growth made in 12 consecutive months. Children having this kind of a record are designated in this bulletin as “complete record” cases. _ The complete records were classified according to the date of the record year in which the child was weighed. Three primary groups thus resulted. VARIATIONS OF GROWTH IN WEIGHT AND HiEliGHT OF CHILDREN 13 Group A included the children who had records for both record years; group B had records for 1929 only; group C for 1930 only. As may be seen in Table 2 these three groups together constitute about one-third of the total number in each race on the weighing rolls. That the smaller U TOTAL GROUP COMPLETE RECORD GROUP WHITE CHILDREN ONnbOJ PERCENTAGE OF C ILDREII JAN. FEB. ma. ma. MAY JUNE JULY AUG. SEPT. ocr. NOV. mac. BIRTH mourn E14 Q12 MEXICAN cnzwm 51o 8 a g e 4 E2 fi @- o am. FEB. ma. ma. mu JUNE JULY we. SEPT. ocr. NOV. one. 31am mourn 514 M 5 12 unono cnztnnnn H 51o g- a g; a =3 4 E a z =- o JAN. FEB. ma. ma. my JUNE JULY mo. SEPT. ocr. NOV. use. BIRTH MONTH Fig. 4. Distribution according to birth-month of the total number of children weighed from 1 to 21 times within the period of data collection, and of the number who had “complete records” of Weighing through one or both record years. i group of complete record cases is as satisfactory a sample as the corres- ponding larger group in each race, is indicated by the graphic presentation of data in Figures 3 and 4. The striking similarity is evident in the approximately equal representation of the sexes, and in the distribution of age groups and of birth months. 14 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION Of groups A, B, and C, only Group A, which included the same children in both record years, was analyzed separately. Group A was combined with Group B to give the largest possible number of “complete records” for 1929, and (for the same reason) with group C for 1930. The larger groups were desired for subclasses within each race. In all analyses with groups A, A+B, and A+C, the record years of 1929 and 1930 were treated separately so that the findings for seasonal aspects of growth in one year could serve as a check on the other. This was thought preferable to averaging the two record years. A fourth smaller representation for each race, group X, was derived from the “complete record” cases. This group X (Table 2) constituted about 10 per cent of the “complete record” cases and included only those children whose every weight change, both monthly and summer, was either a gain, or zero. Selection of this group was based upon the con- sideration that having shown no loss at any weighing period, these children were probably the freest from factors disturbing growth and hence might more truly represent the normal course of growth for indi- viduals than would be apparent from the trends shown by the groups which include children who lost weight occasionally. Group X is used chiefly for examination of individual records, but it is also treated as a group for comparison with groups A+B and A+C, which include both gainers and losers at each weighing period. Seasonal Variation of Growth in Weight Race Groups Average Net Gains Derived from Group Weights. In all calculations of average weight per child the total group weight was divided by the number of children weighed. Gains (average per child, or total for the group during any selected period, month, summer, or year) were de- termined by subtracting either the average or total weight at a given weighing period from the corresponding (average or total) weight at the appropriate preceding weighing period. Monthly and seasonal gains as a percentage of the yearly gain were derived in the usual manner. Each monthly gain is recorded in the tables under the month which was the first of the two weighings between which the gain was made. Thus March weight minus February weight equals February gain, which is recorded under February. An arbitrary division of the year into the three seasons which most naturally fit into the “record year” and the schedule of weighing followed in this study places February, March, and April in spring, May to September inclusive in summer, and October to January inclusive in fall-winter, hereafter referred to as fall. In the record year of 1929 the negroes were not Weighed in May; hence their gain for the month of April 1929 cannot be calculated. The spring season for the negroes includes only 2 months, February and March; the summer includes 6 months, April through September. VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 15 The average gain per child for 12 months, during the consecutive weigh- ing intervals of the year and the three seasons, has been determined for each race by the use of the smaller group and the larger group in each record year—group A, and group A-l-B in 1929; group A, and group A+C in 1930. The data are given in Table 3. The distribution of the monthly and summer gains as percentage of the yearly gain is shown graphically in Figure 5. . For each race, the data present a strikingly similar picture of growth in the two record years with both the smaller and larger groups. This, along with other considerations, is evidence that the percentage distri- bution of the yearly gain through each record year is acceptable-despite some variation in length of the intervals. The weighing of the major portion of the children in group A was continued through March, April, and May of 1931. The average net gains per child in February for the white group was 0.99 pound in 1929, 0.42 pound in 1930, 0.96 pound in 1931; for Mexican, 0.92 pound in 1929, 0.67 pound in 1930, 1.02 pounds in 1931; and for negro, 0.70 pound in 1929, 0.49 pound in 1930, 1.28 pounds in 1931. The length of the February interval for white children in the three years in order was 35, 35, and 28 days. Yet their gain in February 1931 was nearer that of 1929 than that of 1929 and 1930 were to each other. The February intervals for Mexicans were 35, 33, and 35 days, and for negroes 34, 35, and 31 days in the three years; yet all three races showed lower gains in February of 1930 than in February of 1929 or 1931. The gain in the long October interval in 1929 for white children is matched by the gain of their shorter October interval in 1930. It is also approxi- mately equalled by the gains of the Mexican children in October inter- vals which were shorter than for the white children each year. A smaller percentage of the yearly gain of white children was made in the short November interval of 1929 than in the longer November interval of 1930, but this was not true of Mexican and negro groups. With the exception of the A+C group of Mexicans, the November 1929 gains of Mexicans and negroes equalled or exceeded the gains of corresponding groups in 1930. What- ever effect the variation in the length of interval may have had appears to have been over-balanced by some other factors influencing weight gains in the several months. Among the three race groups, similarity is much more conspicious than difference in distribution of gains through the divisions of the year. In all cases the four fall months, October through January, show more than one-third of the total gains for the year; and for all but group A of the negroes in 1930 the average monthly percentage gain in fall is greater than in either spring or summer for the same groups. The only note- worthy difference among the race groups is in the relative proportion of the gains made in summer and spring. The negro children gained relatively more than the white in summer and less in spring. The Mexicans held an intermediate position between the other two races. In 1930 the Mexican groups, like the negroes, show an average monthly percentage gain in summer only a little less than their average fall gain, with their gmfiqflunxil. . 16 BULLETIN NO. 510, TEXAS- AGRICULTURAL EXPERIMENT STATION dag mo“ wnouwa M55303 nwxonnfi: C.» wa .290 ommfl mo yaw.» vacuum #50 QQGO mug mo as?» wnooon afloflwfloanu floswmw? w .5932. “Ea zadshnwk fifinmm “awnEwuQwm-flaalw Awmmfi MOM UHOOUk CQXOHQCU flaw Udfi 05>? 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NN.N_E.N NNN N3 Ohwoz \_ NNN NNN N.NN N.2_N.N FN NN S: Héifiwiva _N.N aw: NNQNN.N_NN.N_NN.N_NN.N:H.N Gimmd 2N NN NNNQNNNE NNNH _ < N3 ZN NNN d3_N.N TN Ni EN Ne Taiwd __N.N TNN NNNTSN”NN.NT.N.%N.N”NN.N wfiifiwo Nwé NN ~52? k 65 1:30 dQww-ENE san flsflowdwm mmwwaoim Zsuflowm wflufimw 5H 1 m BMEN cw _ ism 3.30% mo ouwunwonwm ma 3am owxnw>< 2.56m E 5am wmwawie. moo: m u: suao E iuuwfiso we Emu 3H3» 3 5.350 .- E Nina icomnom can >EN=oE oMnuoiN m: c321 Na E328 E i-Bouu we new???» _ uicwnam .m 03in. 17 VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN .22.!» macaw» suwo E wowu sumo mo 9502M .8222 us“ wcw aoisfiw one hm GUNS 5am 2.52m o5. no wmwwcwouwn ww 22am nwfififlm wad hzufiofi we nomusnuaamwfi .m .22 nfiTmitil 12 .8» i 2... .5. i v.3 A8 i Q3 .25 |dm< . . i.gwz.zmmmiomfl= mfimieqzfii 0.2 .89 T... .>2_i i2 s28 i Q2. 12.2w I 2: ifinéfii Qwéii m.» .B~i 5.33m o fisi Q2 .54 T; .8: 22 .25 i 2.2 Q8 i 2N» 42mm I I: iwmw 2.2 éi imd 5E i225 5.2+ f... .2» i ed .36 i QQF-POZ i 12 A8 i 1N... .25 I .95. H.» .8... i228: mqoi ms .5» i 2m .23 i m5 .5. i 0.2 d8 i >6» 22w I 5i w.» .5: i 92 .5.» i .52 2w 6 25.7 0.2 .52. i n6 .822 i2... .84 0.2 .98 i Q3 2.2m I i: i fiméii finds; i2 d": i225 WO-w ~Ou¢ 0 O n 0 oH .5 - - ll v bum“ 0 . i 3i Q 2 8a i _. 2. B; n. 2 8 . n .3 2km 52 .5: m. HE 05m: I wnmi, w.» iii 2S .89 imd égi 92 4.00 i Q3 4.2m I i: i}. éfiifiwééii. AME i .52 ¢m 3.2.76 Jfiéi 22 .23 i 22 .8: i 92 £8 i 23 2&5 I ii 92 5s i...@.mw.._i§H§ wfiiI 9m .5» i 2m .98 i s. éii i2 4.8 i Q3 .25.. I .52 H6 .5» i228.“ ‘L 2.; w... .n<_.i 2.3 .35 i 2.2 $2. i 2.2 .30 i n4.» Ab... I 5i Wiwgngi i3 .8... i .5: 6 .25 i w...“ 22 2.8 i i3 urn» I .2: i...» 45.7fm i 2x2 .8... iBH s. I w w mw n82 . . w. o M flfluu n1 a 1A il 18 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION lowest rate of gain in spring; in the 1929 group, however, the Mexicans resemble the White children in that the spring and summer rates in the same group were practically the same, or differed little. Only two outstanding features of gains made in single, months appear. October was consistently a good gaining month, and April was consistently a poor gaining month. October gains range in the twelve groups from 11.3 per cent to 16.1 per cent of the yearly gain, and April gains from 1.4 per cent to 6.4 per cent among the ten groups for which April gain could be determined. Among the groups of white children, approximately one-half as much gain Was made in the single month of October as in the 4 preceding five summer months; among the Mexican groups, one-third as much; and in two of the four negro groups, one-fourth as much as in the preceding five months and six months respectively. No generalization can be made concerning the proportion of the yearly growth in any other single month that will always hold for the three races. March was usually but not always a poor gaining month, six of ten groups showing no better gains for March than April; two groups (A, and A+C) for white children showing excellent gains (11 per cent and 12 per cent of the yearly gain); and two groups (A, and A-l-B) for the Mexican showing moderate gains (7.4 per cent and 7.5 per cent of the yearly total). The first fall weighing of 1930 for all Mexican and negro children in group A and for all but one Mexican and six negro children in the A+C group was made in September. Group A of Mexicans gained in September 1.08 pounds, in October 1.23 pounds; group A+C gained in September 0.93 pound, in October 1.15 pounds. Group A of negroes gained in September 1.02 pounds, in October 0.92 pound; group A+C gained in September 0.86 pound, in October 0.95 pound. From these data September of 1930 is seen to have been practically as good "a gaining month as October for the negro and Mexican children. The race differences found in seasonal variation of growth in weight are so small that they can scarcely be attributed to inherent racial char- acteristics, without elimination of other factors that may influence growth, and such elimination cannot be made from the data of this study. The variation found between the three races and within the Mexican race, in relative proportion of the yearly gain made in spring and summer, suggests that some other factor was exerting an effect upon rate of gaining, along with any biological phenomenon which tends to express itself in a rythmic seasonal variation in growth. The exceptionally good gains in October and conspicuously lower gains in April are in harmony with the findings of ‘the recent study of the U. S. Public Health Service with white children in Hagerstown, Mary» land, reported by Palmer (17), and also with those of Turner (24) for fourth to seventh grade pupils in the schools of Boston. The Texas children, however, do not exhibit the gradual reduction in rate of growth through the subsequent fall and winter months that Palmer notes for the Maryland children. That April and other spring months need not be a poor gaining time has been demonstrated recently by Thompson and Scholtz VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 19 (23) with 24 Jewish girls 6 to 16 years of age, in Southern California. These girls were placed under a closely supervised health routine which curtailed exercise, provided for more than the usual number of hours in bed each day, and maintained a generous Well-selected diet. From January 25 to May 10, 17 of these 24 girls equaled or exceeded their expected gain in weight for the entire year. Some of them made gains from twice to several times as great as the expected yearly gain, and certainly more than reasonably could be attributed to the accelerated rate characteristic of an under-nourished individual. What influences among these Texas children may have been responsible for the exceptional gains in October and the conspicuous lack of gains in April is a question of considerable interest calling for further study. Individual Monthly Weight Changes. A further comparison of the gains made by each race in the single months of each record year is based on the monthly weight changes of each individual in the several groups. To effect the greatest possible accuracy within the limits of these data, the monthly changes in weight were calculated for only those children who were weighed in the same quarter of the school day at each two consecutive weighing dates under consideration. Since the larger and smaller groups in each race gave essentially the same picture of growth, only the two groups containing the largest numbers were used for this analysis (A+B for 1929 and A+C for 1930). The manner in which the gainers and losers contributed to the average net gain may be judged from the data in Tables 4 and 5. Table 4 presents a summary of the individual Weight changes for the 7 months in each record year; Table 5 shows the detailed data for each of the 7 months. From the summary of all monthly changes made by each race (Table 4) the predominance of similarities over differences in the three races is evident; but at the same time one point of variance of the negroes from the other two races is plain. The ratio of number of gainers to number of losers is 2.99 to 1 among Mexican children, 2.94 to 1 among white children, and 2.23 to 1 among negro children. The average monthly gain per child derived from the net gain of the entire group is practically the same for white and Mexican children (0.72 and 0.71 pound, respectively, for the two record years together), but is slightly lower for the negro (0.61 pound). In contrast, the average monthly gain per child based upon the av- erage actual increments in the gaining group of each race is a trifle greater for the negro than for the other two races, as would be expected from the greater proportion of children 13 years or over among the negroes, as is noted later. The average monthly loss per child calculated from the actual total losses were respectively for the two record years, white children 0.61 and 0.55 pound; Mexican 0.61 and. 0.62 pound; negro 0.78 and 0.70 pound. The distribution of actual individual monthly gains and losses is closely similar in the two record years for‘ each race, and is also similar for the three races in each record year. About 1/5 of the children had monthly gains less than 1k pound; about % of them gained from 8 to 15 ounces; 20 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION wowww MEAMHQB oiudowmflou 03.... Suwo E haw on» mo nwuawfid 05am of. E wwFwmwB 0.33 domawpwwmmcou .595 on? mHwH-wriwnm wmofi 3:0 now wwfimHsoHwo ouwB $98.3 EH25" , _ A _ _ _ _ p.» (a. we Hm w.HH mm QEHNN m? m5 wHwzam wdH 5N Q2 ma” mam m5 >.H~.._ a3 mp5 3H H" 3N Sm SS E8 Hwd $3 H309 _ 3. w..." m6 § H.HH S QvflmmH gig Qfiafi 3H vHH HiwH mvH 9mm 3N Emu mum E20 mmH H" H.N o2. 53 52 Hwé 8E .52 _ eéwz w.» mm w.» pm Q2 5. “.3 HoH wmiwfi NEQN wdH cHH H.wH wmH m3 2N Hi2 5H $8 £4 Huiw Em 8w S2 Hwd NHQH am? od pH w...” Hm mdH N... 2a m3 QLSN airs.“ HdH Eu Q3 3» 3N m3 2L 3.» N3. 3H H“ 3N Eb vHwH mama Hvd B§ HEPH. 1.. H. m6 3 wdH 5 Q3 3 YwHLcHQH HJZNNH wdH m3 HAN N2 m3 Hfi HiHfl m2 8... >H.H H5.” 3N 2w $2 $5 Efi 32 cwouafi m..." oH ma. NH NNH m” 5a mm 13:1 mdHTmH 5: 3H w...“ m3 v.3 3N 3E HwH 8... £4 H“ .5 3a Em 3S 3.6 HHNH $2 a.» Hm 9m mm. wdH Q. Q3 wwH Hiram wfira» Q3 8N QHN .3. Hdm m2 9% m3 $2 mH.H HQQN 2:. S8 $5 E3 $3 HnpoH .3 NH .3 3 m6 w» Q3 mHH “£23m 312: d3 ovH 2N 3N Q2 N3 Q3 gm £5 >H.H H" 2 2» $2 $2 2.... 22 33 m3; o.» a c6 mH wHH 3 “.5 m» Naiafi Nsia: HtmH m2 3a a: 1mm 2N 3i 3N Hwd Hm.H H“ H.” Ho» 3a HmmH 3.6 $2 mwfi g _...z_ w» _.°z $ _6z_ Q. _...z_ Q. 7.2 Q Fz fi. _...z fix. _...z w» _...z_ § _...z_.w.~q .25 muwmo- Q5 \ . . . . . . . V V 67H o» mHwwoH EocHaM 67H .32? mama» u. Q mwvmfin; u-ov nHHH £0 mH-w do To .|._,,.| Q -m%omH.n§ Aw» nHH do Ea do 7H w» w .A mmwfim dZ dZ H.305 non 5% Ho 67H H: w w H: AH a: a w H: c: H s m. ma» HQWHM awn .>< .32» 005m a a "o. mnomowH mwwcfiwm. m ~m~ m m. || Hioowfi I m. Hwwcnnu pfiwmob» mesa: mwwwO pa?» sumo mo .55.. roofl .502 raoO 35¢ ...HwH>H rnwh E owwE fiHwHwB 5 mowcaso hificofi mo coHusfippwmnH momcwsu Hnwmo? fificofi HmHEZwcH Quouw H.309 an?» vacuum sue» E 23:2: H. .3“ “Emma? E 3.95:0 3-3-55 u: muuiinw é ~25. VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 21 about 1/5 gained 1 pound to 1 pound 7 ounces; the remainder gained higher amounts. Losses of less than V; pound \were shown by nearly lé of each race; almost 1/3 of each race lost between 8 ounces and 1 pound; the remainder 10st higher amounts. The data in Table 5 depict the growth of the three races by months in each record year. It is evident that while the negroes have less variation than do either of the Mexican groups or either of the white groups in the ratio of number of gainers to number of losers, the four fall months to- gether show in every instance a higher ratio of gainers to losers than do the three spring months. With but one exception (March 1930 for negroes), April has the lowest ratio of gainers to losers, the range for the three races being from 1.1 (white group 1929) to 1.9 (white group 1930). October has the highest ratio of gainers to losers among all the months except February 1929 for white and for Mexican children. The range of ratios of gainers to losers in October is from 3.0 (negro 1929) to 8.4 (Mexican 1930). There is a tendency, which is regular only in the Mexican and negro groups in 1929, for the ratios to become gradually smaller from February through April, and again from October through January, with February the best spring month and October the best fall month for num- bers of children to gain weight. March 1930 for white children and November 1929 for negro, show high ratios of gainers. With respect to the magnitude of the average monthly individual gains, however, no such gradation is evident. In fact, the average individual monthly gains per child show that October, while always an excellent gaining month, is fairly comparable with two or three other months in the same record year rather than an exceptionally good month for gains as indicated by the average gain per child based on the net gains of the total group. Nor are the average individual losses lowest in October of a given record year except for the white children. Most of the average individual monthly gains including those of April were near 1 to 1.25 pounds; the range for the three races is from 0.75 pound to 1.66 pounds. In a comparison of the percentage distribution of actual individual monthly gains in the separate months with the average of the 7 months‘ in each record year, April shows consistently somewhat higher percentages thah the average in the interval of 1 to 7 ounces, and somewhat lower percentages in the intervals from 1 pound 8 ounces to 2 pounds and over; October exactly reverses this relationship, showing a lower percentage of children who gained less than 1/2 pound and a higher percentage of children who added more than 1% pounds to their weight. In this respect, March resembles April among Mexican and negro children; January resem- bles October in both years for the Mexican and the 1929 negro groups; and November resembles October in the 1930 negro group. The distribution of the actual losses in separate months shows, on the whole, less variation from the average of the 7 months than is true of the distribution of gains. .. 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Q: domHuw d0 NEH [HAW 3 fi mHwmOH v0 .02 dz HGHOH. uwfi MO HQ .2: m kown: | £ H ma: N | how QHH | pH H m W. m...» B wHNHWHHmHw Ho oZ Q _ 5am dz oflnwn» m mi". .. m .3. w» w m mhwmOflm mhwflfifiw m: m: HQMHHNEQ uSMMQg MHHTINS mommO HfiwHHOS vlw 3 ll 5.98 m wowcwsu HHHMHM? fificofi Ho QQHHHSTSBQ wwmidso "Ewmo? 3.1.5.8. Hanwriz: HduorH. 24 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION The individual monthly weight changes provide a picture 0f growth during the 7 months in each record year that is essentially the same for all three races. The chief racial difference is in the ratio of the number of gainers to the number of losers, an average of approximately 3 times as many white and Mexican children having gained each month as lost, while only 2 times as many negroes gained as lost. Some factor (or factors) somewhat more favorable to growth in fall months than spring months was apparently operative. The effect found expression more in the greater proportion of children who gained in fall than in spring, than in the average amount of weight gained by the gaining group, or lost by the losing group. April and October are conspicuous, the, former for poorer gains, the latter for better, but they are less outstanding among the single months when individual changes in weight arelconsidered than when net gains of the entire group are used to determine average monthly gain per child. Sex Groups The comparative average net gains derived from group weights of the two sexes in each race are shown by the data in Table 6. The yearly gain of the white girls exceeded that of the white boys’ by from 1 to 3 pounds, Mexican girls that of the Mexican boys by from 1% to 3 pounds, while the negro boys and girls differed by from 1/2 to 2 pounds, the boys having the advantage in the two larger groups which included a few more boys of 13 years or over. This sex difference in favor of the Mexican and white girls and the negro girls in‘2 of 4 groups was due, no doubt, to the influence of gains of the adolescent girls who experience this acceleration of growth at an earlier age than do boys. A larger pro- portion of the negro children was 13 years of age or over than was the case in the other two races and hence included more adolescent boys. The distribution of the average gain per child as percentage of the yearly gain through the single months and the summer period present, in each record year, strikingly similar pictures for the two sexes, especially in the case of the white children. In all twelve groups, October as a single month is outstanding with large, close, and oftentimes nearly identical percentages of the yearly gain for boys and girls. April is conspicuous for the low percentage of the yearly gain, being never as much as 1/12 of the yearly gain, and once even showing a loss. April also exhibits the most frequent sex differences. Three of the four groups of the white girls and two of the four groups of the Mexican girls made slightly greater gains in April than did the boys in the corresponding groups, but the gains of negro boys in April exceeded those of the girls. If for the white children April gain is added to the summer gain in each group, the resulting six months period shows the same percentage of the yearly growth for boys and girls in three groups, and in the fourth, the girls have only 5 per cent more of their gain in the summer than do the boys. The only other single months showing sex differences worthy of mention are adjacent spring months (February and March) in two of the 25 VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN fimnfimunmwémunwfiouum: now mum.“ umfiisww .... min... mwocwoou mmm. . _ ww w... ...w ww. ...w.. ...w ww ...w w..... ..w... ww... ..w... www NN... ...N... ww... ..N... _ ww _ 22o ..w... __ 0+4 w.. ...... 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Quin Gm Lisw 0H 2.2.0.... 29.6 flH .3509. Bwdmw cH Lbnw .5 5.58 3min flH hiam? .02.. 0200mm w 3 5mm miamz we mwnwcmmama m mm 5mm mmwum>< 20.500 c. 5am mmwam>¢ 59w m-uam.» o» G033... E 35am umEE-i 1:: .2552: 0MOhw>d ..... 530.1 ma mun.- Juum i. wit. van who: a0 23mm? E Jftouu u: Gian?!» iwicuamm 6 05GB 26 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION four Mexican groups, and adjacent fall months (December and January) in two of the four white groups, all four of the Mexican groups, and two of the four negro groups. In all of these ten groups, each sex had a higher percentage of the yearly gain in one month and a lower percentage in the adjacent one. In each, the order of the higher and lower gain is reversed between the sexes. ~If the gains over the two adjacent months are combined, sex differences in them entirely disappear among the white children. In five other groups neither sex has over 3 per cent more of the gain in theseadjacent months than does the other sex. In the remaining groups, two of Mexican boys and one of negro girls have respectively 6 per cent, 12 per cent, and 7 per cent more of their gain in December and January than do the groups of opposite sex in each case. Summer gains among white boys and girls vary irregularly,’ the girls slightly exceeding the boys’ gain once, equalling it once, and being less twice»; but as was previously mentioned, when April gains are added to the following five-month period, sex difference is nil in three cases, and negligible in the fourth. Among Mexican children the girls consistently gain a little more of their yearly total in summer than do the boys in the corresponding group; but the gain of the negro boys was relatively a little more in summer than was that of the girls in three of four groups, and the girls exceeded the boys in the fourth group. In the last three fall months, the percentage of the yearly gain of the four groups of Mexi- can boys is in round numbers respectively 33, 28, 31, and 34, with corres- ponding percentages for the girls of 25, 24, 24, and 18 the reverse of the sex differences in summer. Among negroes, the girls’ percentage of the yearly gain in the last three months was approximately the same as the boys’ in two groups, and was more in two, the values in whole numbers being for boys 26, 24, 23, and 27, and for the girls 27, 31, 28, and 25 per cent. A The identical gains of white boys and white girls in three consecutive divisions of a 12-month period, February and March, April through Sep- tember, and October through January, is contrary to the differential sex difference in seasonal variation reported by Palmer (17) for white school children of Hagerstown, Maryland. Palmer reports that his data “indicate that, although girls grow more rapidly than boys during the whole interval from the tenth to the fourteenth year, it is principally during the spring and summer that the velocities of growth for girls greatly exceed those for boys . . . .,” and “that, although boys grow more rapidly than girls during the fourteenth and fifteenth years, it is principally during the fall and winter that rates for boys greatly surpass those for girls.” An im- portant difference in the two studies is that the gains of the Texas children are based on nude weights, whereas the weights used for the Maryland children were those determined, in “regular indoor clothing” and “without shoes, vests, sweaters, and coats.” Differences between maxi- mum and minimum weights of clothing worn by white school children in Texas (22) have been found frequently to be % pound, 3A pound, and VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 27 1 pound. Such magnitudes are comparable with the average monthly gain as recorded in Table 5. Few of the average gains even in October much exceed 1 pound. This contrast between the two studies indicates that the factor of clothing should have serious consideration in connection with the seasonal variation in weight. Because of the identity of the white boys and girls in their seasonal variation of growth in weight, and the reversed positions of Mexican and negro boys and girls with respect to summer and fall gains, there appears to be no indication in the data of this study of an inherent sex difference in seasonal variation. Such small and inconsistent sex differences as appear must find explanation in some other factor. Age Groups The usual earlier beginning of adolescence in girls necessitates separate analysis for the two sexes by age groups in each race. The numbers com- Table 7. Yearly gain in weight made by age groups White children I Mexican children Negro children I I I Sex Age’ 1929 1930 1929 _ 1930 1929 1930 years N°- Lbs. NO- Lbs. NO- Lbs. N°- Lbs. N°- Lbs. Ne- Lbs. cases cases cases cases cases cases I I I I I I I 6 PI I I I 1 7 20 6.39 13 7.86 2 2 4 6 8 17 6.65 30 6.28 9 4.72 5 16 6.96 4 9 30 6.74 30 6.15 12 6.20 11 5.42 10 6.31 18 6.18 10 29 8.80 28 6.99 23 6.60 15 6.82 9 6.49 14 6.41 Boys 11 I 4 18 11.16 21 7.97 18 7.45 9 5.92 13 6.80 12 I 2 4 15 8.97 17 7.29 11 11.18 14 10.13 13 5 .3 13 13.85 17 11.16 14 4 1 8 13.27 12 15.06 15'. 1 2- 3 8 12.38 16 I 2 1 I I I All I 102 7.29 125 6.84 92 7.69 74 7.19 86 9.18 107 9.10 I 5 | 1 6 I 4 1 7 I 18 6.47 17 5.17 1 9 6.12 3 8 20 8.07 19 5 80 7 5 12 5.63 11 5.72 9 21 7.90 31 8.49 17 8.00 14 6.64 14 6.95 17 5.88 10 I 14 10.04 22 9.78 23 10.42 25 9.64 19 11.56 6 8.58 Girls 11 I 3 8 8.43 19 9.34 22 11.49 13 12.91 17 9.64 12 I 1 I 1 10 10.46 18 10.23 21 11.11 12 10.05 13 I I I 2 I 4 9 ' 9.08 10 8.14 13 8.22 I 14 3 11 6.92 5 I IBI 1 5 7 I 16 1 4 I 171 1 1 I I I I I I All I 77 I 8.27 104 I 7.88 I 81 9.18 98 8.68 120 8.66 93 7.24 lCalculations were made only for groups consisting of 8 or more individuals. posing the several age groups in each sex of the three races, and the average 12-month gain per child in each group for each record year are shown in Table 7. Calculations were made only for groups consisting of 8 or more individuals. As is readily evident in the case of the negro children and the Mexican girls, the accelerated rise in yearly gain begins ..3on333o333ow|=.333< iofififiw 33303333 3333a hnwsnnwh ..M33m.333w 600.523 30km N ..3wn3.33w3-33vm|m.333¢ 6.3mm: 3cm mug 30333333353 3 _ 3 _ _ . _ _ _ _ _ _ _ _ _ _ _ . 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G N O umwm. V N J . . . . . . . . no . 5.9m Lusm mnunofi 26:05 6:258 m 6 m w» m m m. m m m £6.65. m m W 32.6% W w“ H \ |6|| ‘nwmfiwl . Hung QMdhQ/d m... m» m. a m Zdrfl NGTHQW n 6622: Jidw n X 5am omaunoouoa .55 _ ficofi 26.5w zH finofi 265m cH fifii 365m cH >v~ao6w m d M M hHHHfiHoE wmwuwiw mcowmwm cH _ Q m D. 5am hHnwwh mo owwuflounoQ 6w 5am @9295. 6655a E nmww wwdao>< UQHHHHMQGOUIHHQD a m6 5.3m 0M: auuo 10E? u: .HH-ohm 0H2?» 65$ J33 flommuunicu E wan flmuu h-hdflh o» ion-Sou E 65am Hnicmuom 1:.» 6135:: c6932" .3 530:6 mu coma nuuo E N06 h: 253m owe E siwcuw .6 36am. 3O BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION with the 10-year-old girls and with the 12-year-old boys. Owing to the nearly uniform gains made in a year by the slower gainers, and similarly by the faster gainers, it seemed logical to form two age groups for each sex of negro children--9-, 10-, a.nd 11-year-old boys to compare with those 12, 13, and 14 years old, and 8- and 9-year-old girls to com- pare with 10-, 11-, and 12-year-olds. The slower gainers among the Mexican girls (9-year-olds) were compared with the faster gainers (10- to 12-year-olds). This comparison of the 9-year-olds with groups 3 and 41/2 times as large seemed legitimate because the 10-year-old group alone had a distribution of gains almost identical with that of the 10-, 11-, and 12-year-olds together. "Mexican boys and white children included too few of those in or approaching adolescence to show marked difference in a 12- month gain of age groups. Approximately 1/2 of the white children and 1/3 of the Mexican boys were in the 9-year and 10- year age groups. Considering these facts, only the 9- and 10-year-old white children and Mexican boys were chosen for this analysis. The well recognized acceleration of growth whichaccompanies adolescence adds interest to the distribution through the year of gains referred to age. The distribution over the year of the average gains per child in the selected age groups in comparison with the gains of the total group from which the age groups were taken is shown in Table 8. A graphic presentation of these data is given in Figures 6, 7, and 8 respec- tively for white, Mexican, and negro groups. In general, the selected age groups in each sex of each race present a picture of growth which closely resembles that of the corresponding race and sex group which includes all ages. White children of the 9- and 10-year groups, like their all-ages group, made relatively more of their gain in the fall than in either spring or summer. Among both boys and girls the relationship between spring and summer rates of growth, as indicated by the average monthly percentage gain, is not consistent in the two record years when the 9-year- olds and 10-year-olds are compared. Some of the 9-year-old groups gained relatively more in spring than in summer and others less in spring than summer, and similarly for the 10-year-olds. Hence no distinctive age group differences in the seasonal gains can be pointed out from the be- havior of these 9- and 10-year-old white boys and girls. Mexican boys of 9 and 10 years, like the white children, exhibit reversals of spring and summer rates in the two record years; but on the whole these 9- and 10-year-old Mexican groups conform to the general distribution of seasonal rates shown by the total number of Mexican boys. The Mexican girls afford the only instance in which there is a fairly consistent difference in the performance of age groups. In both record years the 9-year-olds gained relatively more of their yearly increment to Weight in the fall months than did the 10 to 12-year-olds. The average monthly gains in spring and summer as a percentage of the yearly gains for the 9-year-olds were closer to each other than either was to the gains made in the fall, while for the\10-year-olds average monthly percentage gains for summer and fall were closer to each other than either was to the 31 VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN ddonw :0?" is: Mimwfioflmonaoo ws» Si? Gommuafiioo E flmuwflflo 35B mo 0.50.5. vmw @0323 3 25E 5mm .253.» 33 mo wwmunwoawa mm 050w uQEESm win 25:08 mo iomunfiauwmfl é .urm 3H 03% 0.5 :3. 5% 0.3 .>0= _ 0.2 d8 ? 500 .25.. I .5. _~..m.~i 0.0 J2: é m.» .02 fiamm. m 00 2.0 % 3. ._§._ 0.2 .80 _ Ni .>0= _ Q2 .50 _ 0.3 $.90 I i: T... 5i 2 .58 _ 0;. .0»... Tn 2 m0 o m 3 2i 10 ii. é 0.2 6E _ 0.2 .>.0= _ T3 .80 _ 0.2 $5 IE9 Tees; i0 .59 _ Z .02 T» 0 2. 30% 0.2 .25. _ 0.0 .80 T.....>0l 0.2 4.8 _ 0.3 .2»... I E. 70.0.5.4 ¢.m.m0= 0 2 .80 i3 5mm I i: 0.2 .3 T5515 0 u: $8 7 0.2 .5; _ E. .08 _10.>0=_ 0.3 4.00 _ 0.0» 5a.... I :9 T.» 0.0é§_ 0.2 .02 was. m m; vlq 3 05 _I i2 4E. 7.0807646; 0.2 4.8 _ 0.3 .506 I i: _ .20 .9: 0.2 .20 ;.§ S o 8 is; 0.2 5:. i I. .80 _ Nd sol 0.2 4.8 _ 0.3 5m» I ti Tifiw i5; 13 .6... T; 0 a .mm._ s mm wm . u 02 . 3 P... m .. I u 32- BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION 3 N... 5 3 2 3 N no 81S"! IO ‘Ol 5502M :9?“ Bu: Mcmwzamwnuoo o5 :33 comiwmaoo F2 25.2330 cwomxwg mo mnsoau www wwuumxmm >5 mwwE Edm imam» may mo wwwaiwuawfl wd mimwu 222225 wfld ~A~JQCOE mo flomfififiaummfi H 2mm . . . . . . . . . I . . ¢J . . .22- 8am2. N2 28 _ N...» .22 I bi _ N.N .22 T.....m§_m_.fim u Nwi m; .5» _ E2 $2 _ f: .25 _ Q2 2.8 _ N43 .2»... I i: N.» .2: _ 92 .22 m ~ o I Y a u - a 0 ll I ~ o - Gm m8 We .52 1% is. >2 8Q _ N2 >2 _ m2 .28 _ w...» 2.2m bi _ 0.25M _¢N Safissa O 3a 0.2 .25 _ 2.2 .8: _ NRQ .28 _ 2N... .22 I 2: wwnmm 0.2 d2 22C m m... m...“ a VW: w o3 u mm: u“ a .. x u 38 VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN dsoum :33 in: unmwcoamonnao cmuwflsu ofiww: mo £53m own 1302mm .3 owwE 5am 3.3m.» Q3 mo omswcwoawn m.» Elam aofifism win m5 n33 flommuanflou 5 >1$=oE mo iomusnmfimmfi .w . E S... Tnéfi; v.5 .85 _ o.» .8: _ ".2 68 o6» .2»... l .E< 6 . i»? % . . ... 3 o@i_.......=<_._ 8.2 .38 é "a .8» _ 8.2 .38 as» .25.. I éfi _ >6 .fi.T5.Q mo o.‘ , .. . fl 3 8.... .2 _ h: .25 _~.....8=_ 9S ~88 _ ma... .23 l £5 _ g .5... T» 5E TE . . W. u o8 m3; w.» i5. _ NS .88 1 w... ..8= _ 8.2 d8 1 Q3 dfiw ... 5% TL o.» .8» m? w t S 2i .......=<.._ i3 6E T.» .8: _ >5 4.8 _ 83 at» I .52 s.“ N... d2 Ts. 3 $io.¢.=<_._ 8.... .8; _ .298: _ n; 3L a...“ fin» I .52 “us... i. w S. o1l>4 éi 8:: .02 _ N... .8». _ Q2 .._.8 _ fifi a5... I .52 3 a2 . l 1w 2 Gimp; 8.2 .35 _ 12.8,. _ 72 a8 _ as...“ 5mm I £5. 7.85275. mo I» 2.. .21 m5 is. _ qfi .88 768i Q3 a8 _ 8.2 Em» I £5 _.mfl_....@.fil5n. w . . . . . . . . . . I . 8d . . 2 3 Bmfi 82 5:. T.» 8i“: 8i $2 a8 — .3 .25 92 m; E.» 3i m an 0h. N-fin .245 Q.» . . - O .@ . l- - h-Ol-M $0 8.. _. m 8: w z $0 N m. ram E... E. .5; em 3 rwl Q2 43. _ m... .95 13 .88 _ ~50 ab... I .52 1.4.5.: iwdvfln Q 0R “o3 . Sm v0 V” S. H8 n. % n n L$§§JfiE§&3 34 BULLETIN NO. 510, TEXAS, AGRICULTURAL EXPERIMENT STATION gains made in the spring. These differences are small, however, and for this reason, as well as because of the very small numbers in the 9-year-old group, must not be regarded too seriously. The most impressive picture is made by the negroes whose younger age group of each sex gained only about half as many pounds in a year as did the older group. Yet the distribution of the gains through the single months and summer, or through the three seasons, is essentially the same for each age group in each sex as for the whole number of negroes of the corresponding sex. The findings in this study give no evidence that the age of a child is a factor in determining the distribution of a 12-month gain over the seasons of the year. Birth-month Groups The possibility presents itself that the time of year in which a child is born may have a bearing upon the rhythm of his gains through the cycle of successive seasons during his period of growth. It seemed worth- while, despite the small numbers in each race group, to determine what light the data of this study would throw on this point. The children of each race, boys and girls together, were distributed into groups according to birth-month; the average yearly, monthly, and seasonal gains per child were calculated. The birth-month groups together with their yearly gains are given in Table 9. The narrow deviations of the average yearly gain in the birth- month groups from the gain of the corresponding total group is noteworthy. Table 9. Yearly gain in weight made by children grouped according to birth month White children l Mexican children Negro children Birtlil 1929 1930 1929 1930 1929 1930 mont N“ Lbs. NO- Lbs. NO- Lbs. NO- Lbs. N°- Lbs. No- Lbs. cases cases cases cases cases cases Jan. 14 7.17 20 6.18 10 8.45 8 9.06 14 9.85 17 8.64 Feb_ 19 6.77 26 7.80 15 11.15 22 9.63 20 8.02 ‘ 16 8.43 Mar. 13 7.68 l 15 6.33 l 22 l 8.15 19 9.10 23 8.50 15 6.55 Apr. l 6 l 12.00 15 7.36 10 8.81 13 7.04 11 9.52 12 8.20 May 10 l 7.84 30 9.24 14 8.76 11 9.00 26 9.06 26 8.82. June 17 7.93 21 7.70 13 9.28 11 9.01 10 6.99 12 6.63 July 16 7.62 19 6.62 9 4.82 13 8.52 22 9.94 21 10.09 Aug. 21 7.69 26 7.77 19 7.58 15 7.03 22 9.21 15 7.02 Sept. ‘ 18 7.93 15 7.48 17 8.19 16 7.99 16 9.82 18 8.24 Oct_ ‘ 23 7.43 31 7.06 l 10 7.25 17 7.61 14 8.88 20 8.15 Nov. 13 7.90 12 6.79 16 9.17 15 10.40 15 8.85 13 8.40 Dec. 9 7.33 15 7.43 18 7.93 12 7.75 13 9.06 15 8.13 All months 179 7.71 229 7.32 173 8.39 172 8 05 206 8 87 200 8.23 In only 5 of the 72 birth-month groups, did the yearly gain. differ by as much as 2 pounds or more from the average of the total group to which they belong. In view of this fact and of the results of the foregoing analyses, it was decided that a representative birth-month from each 35 VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN aoncfipnww1mpn< £65556 M swung win hnwninfim 65.5w £68m»: nob» aoncfipnomémagw 6.5665 mo.“ 6N6H .3555? 6.66 6.66 6.6 _ N.6 6.6H H6 6.HH 6.6 6.N 6.6 666 6H.H 666 66.6 66.6 666 6N.6 66.6 _ 6N.6 _ 66N j 0+4 _ 6.66 N.66 H.6H 6.6 6.HH 66H 6.6H H.6 6.6 6.6 666 666 66.6 66.H 66.N 666 66.6 666 6H6 6N .660 H66 H66 6.6 H.6 N.6N 6.6 6.6 6.6 6.N 66 NN.6 66.H 66.6 N6.6 N66 66.6 6N6 66.6 .N6.6 6H .656. 666H N66 6.66 N.6 6.6 6.6H 6.6 6.6H 6.6 6.H N.6 66.6 HN.H H6.6 6N.H 6H6 66.6 666 66.6 N66 6N ma? N66 6.66 6.6H 6.6 6.6H 6.6 6.6 H.6 6.6 6.N N6.6 NN.H 66.6 H6.6 6H6 66.6 66.6 6H.6 666 6H duh N a 6.66 H.N6 6.6H __ 6.6 6.6 6.6 6.HH 1.. 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NN6 666 66.6 6N 66E N.N6 N66 6.NH 66 N.6 H._N 6.NH .. .- 6.6 6.6 H6.6 66.6 6H.6 666 66.6 .... .. 66.6 66.6 N66 6N duh A 6.66 6.N6 H.6H 6.6 6.6H 6.6 6.6H N.6 N.6 6.6 66.6 66.H 666 6H.H 66.6 N66 66.6 H66 666 N6H 0+4 6.N6 N.N6 H.6H 66H H.6 H.6H 6.6N 6.6 6.6 6.6 N66 H6.6 66.H 66.H 66.N 6N6 666 666 H6.6 6H .660 6.66 6.66 6.6H 6.6 6.HH 66 6.6H 66 6.6 6.6 66.6 66.6 H6.6 N6.H 66.6 66.6 66.6 666 66.6 6H .6566 666H 6.H6 H.66 6.6H N.6 6.6H 6.6 6.6H 6.6 6.6 6.6 66.6 66.H 666 66.H 66.6 H6.6 N66 66.6 66.6 HH .§H>H 6.66 H66 6.6H 6.6H N.HH 6.6 6.6H 6.6 6.H| 66H 6N.H 66.H 66.6 66.H 66.6 666 6H.61 66.H 66.6 NN 56h W 3 x 6H6 6 6.66 _ 6.HN __ 66 6.6 6.6 6.6H 6.H 6.6 6.NH N66 _ 666 666 6H.H 66.6 6H6 N6.6 66.H 666 __ 66H __ n+4 w. u 666 H H66 6.6H N.6H 6.6H 6.6 6.6H 6.N| 6.6 6.NH 6H.H 666 66.6 6H.H 66.N 6H6: H66 66.6 6N.6 6H .660 666 _ 6.66 N.6H N.HH 66H 6.6 N.6H H.6 66 6.6 66.6 N66 _ 666 6N.H 66.N H6.6 66.6 66.6 H 66.6 6H .654 6N6H 6.66 666 6.6H 6.6 6.6H 6.6H 6.6H 66 6.N N.6H N66 6N.H _ 66.6 66.H _ 66.6 666 HN.6 6N.H 666 6H >mH>H _ 6.66 N66 6.NN 6.6 6.6 66 6.6H 6.61 6.HH 6.HH N6.6 66.6 666 66.H 66.6 6661 6N.H 6N.H 6H.HH 6H .656 6.66 *_ 6.N6 6.6N 6.NH N.6 6.6H H.6H 6.N H.HH 6.6 66.6 66.6 666 6H.H H6.N HN.6 H66 66.6 N6.6 6NN 0+4 666 6.6N 6.NN H.6 6.6H 6.HH 6.6H 6.N 6.NH N.6 666 66.6 N66 6N.H 6H.N 6H6 666 H66 66.6 H6 .660 _ 6.66 6.66 H.6H 6.6 H.6H 66 N.6H 6H1 N.HH 6.6 66.6 N6.H 66.6 6H.H 66.N 6H.61 666 66.6 g 66.6 6N _ .6564‘ 666H 6.66 666 6.NN 6.6 H.6 66 6.HH 6.6 6.6 6.6 666 66.6 666 N6.H 66.6 666 666 _ 66.6 6N.6 6H _ >aH>H H.N6 N.6N 6.6H 6.HH 6.6 H.6H H6H 6.H 6.HH 6.6 666 66.6 N6.H H6.H 6N.N NH.6 N6.6 666 __ 66.6 6N _ xHmnH M 666 N66 H.6N 6.6H 66 6.6 6.6H 6.6 6.6 6.6H 66.H 666 N6.6 66.H 66.N 66.6 666 6H.H __ H6.6 66H M114 w... 6.66 6.66 6.6N H.6H 6.6 6.6 6.6H 6.6 6.6 6.6H 66.6 666 666 H6.H N6.N 66.6 H6.6 66.H 66.6 6N .660 6.66 6.66 6.6N 6.6 6.6H 66 6.NH 6.6 6.6 6.NH 66.6 666 66.6 666 66.N 66.6 66.6 666 66.6 HN .654 6N6H 6.66 6.66 6.6N 6.6H 6.6 6.6 6.6H 6.61 6.6 6.6H 66.H 666 66.6 NH.H 66.N 66.61 66.6 66.H 66.6 6H znH>H 6.66 6.66 6.6N 6.6H 66 6.61 k 6.6H N.6 6.H 6.6H 66.H 66.6 666|_ 66.H 66.N N66 66.6 6H.H 66.6 _ 6H .696 .566 “snow “=54 _ _ _ i _ _ _ 65mm . 1.600 16.62 1.6mm .566 domH _ 5oz .600 x566 _ H62 50h .566 _ donH _ .>oZ _ .660 166E v3.6. §wH>H 69m 66.H HHwrm .65 65.5w _ _ _ _ _ _ _ _ _ 13E .350 155w 155m . wnomdom iH £6505 oHmEm 5H 53505 oHmEm 5H cH 66505 oHmEm 5H ouwwmmyw 5am 3.50m mo wmsanouuom ma 5am oudao>< H @6150.» 5H aim 0Nduo>< . .. . . .f. . .. ...\=..1..E_.:.1.. n11 FL. ...rm..»..v..11...i!ir. 5.6.?» B51115.“ Lw.r_._..vRFF..R.brx. i. .. LIEE 36 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION season should be selected for this analysis. February, May, August, and October appeared satisfactory from the standpoint of numbers when all three races and both record years were taken into account. The average yearly gains per child appropriately divided among the months and seasons and the like data of the corresponding total group are recorded .in Table 10. These data, especially the gains of the three seasons as a percentage of the yearly gain show more consistent results for the record year of 1929 than for 1930. Among white, Mexican, and negro children alike, the four selected birth-month groups in 1929 have a close resemblance to each other and to their respective total groups in the percentage of the yearly gain made in each season. Variations of the different birth- months from the total group are not at all consistent between the two record years. Greater likeness exists, on the whole, among the four birth-month groups in 1929 than between the same birth-month groups in the two record years. It seems justifiable, therefore, to conclude that the data of this study indicate that the time of year in which a child is born is not a factor in determining any seasonal rhythm in his growth in weight. Body-build Groups The type of body-build of children has been found by others to be correlated with their yearly gain in weight. According to the most recent weight-height-age tables of Baldwin and Wood (2), short, stocky (white) children of a given age may be expected to gain less than those of medium build, and medium in turn less than tall slender children, until the maximum yearly gain of the tall group is reached. Short chil- dren continue to gain less than medium in each year of age until those of medium build achieve their maximum yearly gain. Whether children of differing body-build distribute their gains through the year in like or unlike fashion is a question that naturally follows. The data of this study were examined from the viewpoint of body-build as related to seasonal variation of gains in weight. The index of body-build for each child was calculated in a manner similar to that recently used by Lucas and Pryor (12). The index was derived by dividing the width of hips in centimeters by the standing height in centi- meters, and multiplying by 1000 to provide a more convenient working figure. In this study the width of hips was measured with the greater trochanter as the landmark whereas Lucas and Pryor used the iliac crest. The higher the hip-height index, the more ‘stocky the individual. Such an index permits‘ direct comparison of the two sexes and different ages. The largest group of children, A+B for 1929, and A+Cl for 1930, was divided into 3 parts on the basis of body-build indexgthus separating the 25 per cent of most slender build (lowest index) in each group from the middle 50 per cent, and from the upper 25 per cent of most stocky children (highest index group). The yearly gain and the monthly and seasonal gains were then calculated for each body-build group. These data, shown in Table 11, reveal the gains as a percentage of the yearly gain for both 87 VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN £0.85 was zadsanwnm $5.5m “aonfiovnwm|flua< fiofiiflm dmdd éumw: .81.? :8 E uawmws Mflmfifldam lxw E d 2.3 x .8 5 .32 .8 .5? I d . 2:5 “an. v.3 déd dd d4 v2 w: mdfl dd dd 1v dddfi wddd dddd 5% dddwfi wddfi 5d 5.3 dfizd 5.» dd 98E .8 dd.“ pd» ddd 3: vd 0.: HE ddH dd dd. fid 5.8. Emddfi 5am 5.2. vddmd dddd 11d» .53. dddd» 5d dd d5 | d: $2 add ddm vd fiw ddfi d4. W: dd fid dd wddd :2; dddd. pddd 2.2a 5.2 8.2 fiddd dddvm ddd dd mm: .8 ddfi flfi .3... d4» dd d.» dd ddH v.3” m: N61 dd dddv dddd E5 wdAd dfiddd ..... ! 3.7 3.? dmédd wdd C. 98E .8 ddH M ddd did wfi wd dd dd dd .-m dd dd 52$ 2.8 dddd dddd Hwddd dddd wdéd 222. ddd S d5 | d: dddd Yd» ddw ddfi ddfl dd dd v.2 dd dd did .23: 3.5 mmdm :33 dddfi 3.2. 5.2:. ddd dd $2 .8 d3 d? ddd .3; ddn pd dd wdfi .2. mm» A» 3.3 £5. dddd ddéd 3x2: 3.3 3.5 5.3 3%“. 5.3 dd. 88E .8, mdfi w? ddd dd." dd.» dmdfi fid H2 dmd fid d.d dddd dddd 2i 22; ddddd e95“ vddd 3.5 wdédd pdd S. ddfi .. m5 dddfi N 1%. vdd d.5 ddfi vd H: w: dd dd dd w»? dddd 5% 2.5. dfiddfi Hddd mddd mddH Eddd ddd dd $2 .8 EA n ddd div ddH dd dd dmd R3 HA dmd dmi mddd dddd Edd dddd dddS 3nd dddu 3.2 dfiddd 5.3 md 98E .8 ddd m. ddv wdd ddd dd 0.: ddH v3 dd dd m»: 2.5 ddfi. 2.2. dddd 5mm» ddd dddm dddd mdddd 5d dd wdfi | EA dddfi u dd“. add ddd dAH dd dd Q: dd dd ddH 5.3. wddd dddd mwdd ddddfi dd.» m5» min. n53. 2; dd $2 .8 3% ‘.3 3.» 3d ddfi dd! R8 dmdH d4 R3 dd dddd dddfil Edd 8.5. 1...? 5.2 dala 3.5 222% wad E v.85 .8 s: Q5. vdd m2: dd ddd d: ddfi dd HS dd 8.3 dddd 53 wdédfi 33E 56d 33 3.3 wdddd dd.» ddH d5 .. d5 dddfi wdv ddd ddd dd dAH dd vdfi dd dd.“ Hd dddd dddd m?” dddm :32 Hdd dddd dddd wdddd Ed m... $2 .8 ddH % odd ddd ddd Hdfl Md dd HdH .3. d.» dd.“ 225 dfiwd Edd pfia 2.x: dfifi dwdd vddd $43 5m S. v.85 .8 s: ddq fidd ddd HAA dd dd H3 pd dd d4; 5.5 92a. 5.5 ddddfi dfiddfi 23¢ mddd dmdd ddddd dd.» dd d5 - d5 dddfi did déd dd» dd ddH dd odd dd dd ddH dddd 23m 20.: <3; wddd.» ddAH ddda 3.3 23$ ddd dd $3 .8 d3 d2. dawn 1.5. . flaw .25 .23 v.80 13E finch dad 62H 5oz .80 n54 n82 huh dad dwQ .>oZ .80 18E QQ< 05E 59m I. flab .88 wfiinw . . IIII 55m 28E wwim G Q05 Quid i mflwwflfimm B85 EMGG nH Qrmwvay “flue iwwfi MW Wu wnowwow cH A ~ . H A» fi . H cH s . dz mdod mm o d m P e 56M his?» no owddiwoaoQ mu 98.5 mo 5am 130B wwniofi E Qflouw mo 5am 130E imam 3.3m? GHIM 2.3a.» ca Gad-flea i mfiuu iwicdaon wad hdauiafln .3 :32? dd “Ammo? E 5395 we Gcmaamfi; flacmaow \ 180E cans-hue.- OH unmwuoouu wean-cum sandman HO A a ~55. 38 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION single months and seasons to be markedly alike for the three body-build groups within each race for a given record year. Such irregularities as do occur, and these are more common among the negroes than among white and Mexican children, do not consistently distinguish the body-build groups in the two record years. This study, therefore, indicates that the natural body-build of a child, whether stocky, medium, or slender, is not a factor in determining seasonal variation in weight gains. Living Conditions The possibility is recognized that the physical conditions under which a child lives may have a share in determining his course of growth. Conceiv- ably, the home environment might either provide utter freedom for the in- herent growth impulse to express itself, or, if unfavorable, interfere with the natural growth processes. Mitchell (14), reporting a study made by the American Child Health Association with Porto Rican school children, gives evidence of the influence of socio-economic factors upon growth and development. Within the urban group of the Porto Rican children, those from homes having the larger number of rooms and the fewer persons per room showed a tendency to be 'taller, to have greater hip width, larger arm girth, and greater amounts of subcutaneous tissue over the biceps than did children from smaller and more crowded homes. The rural children did not exhibit similar consistent tendencies in the relation of physical development to socio-economic status. Mitchell suggests that the same rating scales as used for the urban children did not distinguish rural families in important socio-economic ways, and that there may be no important differences in the mode of living of various rural classes in ’ a manner to effect the children’s growth. The children who were weighed the last year of this study with Texas school children answered questions as to the number of persons in their respective families and the number and purpose of the rooms in the house in which they lived. From their answers, two indications of living conditions have been evolved—the average number of rooms per person in the house, and the presence or absence of a bathroom. These are recog- nized as inadequate indications of housing conditions in themselves, yet the speculation is probably permissible that in general more physical com- forts and conveniences of living were available to those children who lived under less crowded conditions than to those less fortunate in this respect. The figures in Table 12 show that the white children had more living space in their homes than either Mexican or negro children, in so far as this can be judged by the average number of rooms per person. Less than 1/3 of the white group had as little as 1 room or less per person, while over 4/5 of the Mexican group and nearly 3A of the negro group lived in homes with an average of 1 room or less per person. Only 3 white children out of 243 (1 per cent) had no bathroom, while over 11/3 of the Mexican“ and approximately 1%; of the negro had none. Ten white children had 2 bathrooms in their homes, but no Mexican or negro home had more than 1 bathroom. 39 VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN w...» Q2. m3 5. W3 mém flow o m2 £2 z. 5 . S o2 S $~ 95oz“ 5a ma» .3 3 N5 mam m? \ o 5H o» w u fi m3 3 a: nwufinwg 3 5m NA fim #2 Q8. 9mm NA 3 3N . m mm S. ma." fi. m 3m 33>? Q. dz w» _ dz a.» dz w» dz _ $ dz _ w» _ dz § dz _ w» _ oz 03m. 0:0 _ wnoZ + a Hd _ cd-QA _ mA-HA _ Q3... _ md-Hd .o wow mfioofifiwm 4 GOwHQQ awn wEooa mo non-flan owdzo>< flauwHh. m :32? w.» @500» wcflziuun mofios fir.» 56.5 we Gomunoaonm 253w ooau 35$ Q5. we mafia: E mioeusaan u: 5:55: via cowuon won nEcou u: non-Ga: uuaugu .2- 1332-5 ma mnomfiucau v5.1a dz 035a 40 BULLETIN NO. 510, TEXAS. AGRICULTURAL EXPERIMENT STATION While it has already been shown that the three races in general display " the same seasonal variation in growth, it was thought worth while to de- termine whether difference within each race group existed with reference to the two indications of living conditions. Table 13 shows the seasonal distribution of weight gains as a percentage of the yearly gain for the Table 13. Seasonal distribution of weight gains in relation to two indications of living conditions I Living Yearly Percentage of yearly gain made in 8 g h condition No. gain g 3 3 0f A Springl Summerl Fall m P» Average cases v’. per no. rooms chlld F b _ N per person Lbs. 13132;. April Oct. fl’; 1 or less 27 7.23 21 3 0.5 3 12.4 26 1 1929 1.1-1 5 45 7.27 21 2 5.9 31 1 16.7 25 1 Q 1.6-2 0 18 6.92 14 4 7.2 34 3 11.3 32 8 2i 2.1 & -I— 14 8.00 170 10.1 31 1 16.4 2 4 B 1 or less 66 7.28 16.4 2 3 36.1 17.8 27.3 1930 1.1-1.5 91 7.48 19.0 2 9 .30.7 16.2 31.3 1.6-2.0 42 6.94 19.7 0.4 33.8 16.0 30.0 2.1 & —I— 2O 6.89 12.5 7 3 42.4 5.4 32.4 0.5 or less 31 6.86 19 2 —l.1 35.1 16 2 30.6 1929 0.6-1 0 51 8.38 19 7 1.6 34.6 14 6 29.5 a 1.1-1 5 13 8.85 18 8 5.6 47.7 1 6 17.4 1.6 & + 1 8.69 E 0 5 or less 55 8.37 13 3 5 3 43 7 11.8 26 0 1930 0 6-1 0 91 8.93 12 3 4 1 39 1 14.1 30 4 1 1-1 5 17 7.71 14 8 9 2 36 8 13.1 2 1 1 6 & —I— 4 8.61 0 5 or less 33 8.94 8 4 53.6 13.2 24.8 1929 0 6-1 0 88 8.75 12 4 -_ 53.8 10.2 23.7 O 1 1-1 5 27 10.19 7 1 . 51.2 12.7 29.1 '5}, 1 6 & —I— 15 8.41 5 6 47.7 10.2 36.5 C) z l 0.5 or less 33 6.68 9.8 3 3 51.9 14 8 20.3 1930 0.6-1.0 103 8.12 8.0 6 5 48.0 9 9 27.6 1 1-1 5 44 9.68 10.4 2 9 48.0 12 4 26.4 1 6 & -I— 14 6.69 3.9 2 5 44.7 14 0 34.8 g B31211 8 1929 with 65 8.37 19.4 2.7 38.7 12.6 26.6 ‘Q Without 31 7.09 7 19 3 —-—2.3 32.7 18.8 31.5 0 - th I 106 I 8.80 13.9 5.2 39.4 13.2 28.3 s 19%| 3311mm 61 | 8.29 11.4 4.1 40.8 14.8 29.4 q I with 80 I 9.23 7.4 .. .. 54.3 11.8 26.5 g 1929 without 83 | 8.77 12.7 .. 1 51.2 10.7 25.5 z I with 100 I 8.33 8.0 4.6 47.9 10.6 28.9 193° I without 94 | 7.91 9.4 5.1 48.9 12.5 24.2 1For negro children, spring 1929, February and March; summer 1929, April-September. children in each race grouped according to the average number of rooms per person, and for the Mexican and negro children according to whether their houses have or have not a bathroom. It is evident that within each race and each record year the groups based on either of the two housing conditions made essentially the same proportion of their gain in a given season, confirming the results of other analyses in this study. Such ir- regularities as appear are not consistent as between the two record years VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 41 in any race group, and they are probably no greater than would be expected with such small numbers constituting the\ groups. It is possible that the difference between the poorest and best degrees of living comfort implied by the average number of rooms and the presence or absence of a bath- room in the homes of these children, is not great enough to be reflected in the total growth and the seasonal variation in growth. But in so far as data of this study afford an indication, it is that differences in living comforts did not influence seasonal variation in growth. Constancy of Gain As was previously mentioned, all children in each race whose every weight change throughout ‘one record year, whether for one month or the summer period, was a gain or zero were selected for examination individually, as well as in a group. This group (group X) included in all 95 children, 3 of whom had a record in both record years, so that 98 individual records were available. Out of the 899 children who had complete records, about 10 per cent of the negro, 10 per cent of the Mexican, and 12% per cent of the White children were included in this group X. Despite the surprisingly small proportion of children who met this basis of selection, the groups appear representative from standpoints of age, birth-month, and equal number of the two sexes. In this selection, the records in which the time of day for weighing changed once or twice in the course of the year were retained, provided the weight change was comparable with other changes in the child’s record. These changes (12 for white, 10 for Mexican, and 3 for negro children) derived from dif- ferent time-of-day weighings are marked * in the records of individual gains (Tables 15, 16, and 17). A As a Group. The data for group X considered en masse for each race are presented in Table 14 and in Figures 9 and 10. Owing to the small number of records and to the similarity of the two record years in forego- ing analyses, all records of both 1929 and 1930 for each sex and race group were pooled. The average gain in pounds per child was calcu- lated for each weighing interval, and also the percentage of the yearly gain made in the single months of the weighing schedule and in the three seasons of the record year. This analysis serves in the main to confirm the results obtained with ‘ groups A, A+B, and A-l-C. Again, the distribution of gains through the year is strikingly similar for the three races in that (1) the four fall months together constitute the best gaining season of the three, and the percentage of the yearly gain made in the fall is practically the same for the three races; (2) the races maintained the same order among them- selves as before in the relative gains of spring and summer; and (3) the similarity in the course of growth of the two sexes in each race is even more pronounced in group X than in others used previously. For negro boys and girls the distributions are almost alike. October and April in group X are less conspicuous than in group A, A+B, and A-l-C. October is consistently an excellent gaining month, but with the exception 4.2. BULLETIN NO. 51o, TEXAS AGRICULTURAL EXPERIMENT STATION uoniounwmvflnn< 020222526 "£02222 was auwwnnovm $5.5m .8032. norm“ 2wnEofi2om-=§2< 6N2 dwonmm: 20...? 2.22 2... m... 22... 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VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 43 of the Mexican boys, December and January are approximately as good as October, and November is only a little inferior to the other three fall months in its share of the yearly gain. April, while the poorest single month in "the weighing schedule, is distinctly less than 1/12 of the yearly gain in only one group out of four. March and February also show gains fairly comparable Within leach race with those of November or October._ Because of these better gains in spring months, spring and summer for the white children show greater differences in relative rates WEIGHT H! POUNDS Fig. 9. Curves of growth. Group average weights. Complete record cases (A-l-B and A-l-C) compared with constant gainers (X). of gain than in groups A, A+B, and A+C, the poor rate in summer being thus accentuated. In group X, the Mexicans’ gains in spring were slightly greater than the gains in summer, whereas in their other groups, gains in summer equalled or slightly surpassed those in spring. The spring and summer gains of negroes differ less in group X than in their other groups but in the same direction, with a slightly higher rate in summer than in spring. As Individuals. From the records of individual gains of each child, shown in Tables 15, 16, and 17 for white, Mexican, and negro children respectively, the average monthly gain was calculated in pounds and ounces to the near- est 0.5 ounce for each of the three seasons. The seasonal interrelation- 44 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION don» seam E WSEwm ucwumcoo 0H0? on? mvfim 0A» via when of 3 $55 5am Dado» ma» mo wwwpfioopwa ma mEuM umfiizw was mifiioa we cofisfiuummfi .3 émrm S 8."; 0.3 .25.. _ 9S 6E _ 1m $2 _ i2 a8 _ Q3 in» I .5‘. _ we éi o5 dfiTéG u 2 86L Q2 £3. _ flfi .28 _ Q» 53 _ Q8 d8 _ E3 .25 l éfi Tmr». 2 .9: _ E3 w S 86L v.2 .5» _ 92 $2 _ m; $8 _ ".2 4.8 _ fix" .25 l i: Txuzmmi Z. .59 _ p.952 735a m Y‘ 0 3 8.0L 0.3 is. _ 3. .25 _ o5 .2; _ “.2 .._.8 _ ma» .25 I i: Ta ma; m.» i4: _ .3... 5E L B8 w N EéL 0.2 .5; _ E2 d3 _ m5 .8: _ fifi a8 _ n18 .23 l i: T; éfi _ “.2 as. _ Q2 .2: Tan». YL 8 $4. _ £2 is. _ 12 .25 _ 0.9a; _ Ni a8 % Q3 aEw I i: _ 1m .E< _ 92 .5; _ 0.2 a: i 98m u mama a5 , 2. Rm“ T “ o2 . VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 45 :4 I g | I | 5 §$£§ |1|1|11.:1|1 |1|11111 1.1|1|1|11|1|. ||+1:||| * wfifiw _ _ _~ 0 ____ __ ”””” ”_”_“—“”* '_m _ n!» I 1 § §§%E l+lll|+||HI+ llllllll \lllll|lllI+|l\ llllllll u “Q V1880: 0 ____ ______ _—_- -— m . S “u; 5 5”= Illlllllllll ++++H+++ llllllllllllll ++++++++ > Hid = £2“ ' - ~N m - ' ' '¢ m o o 9mm? . m _ mwm Ho u: O <1‘ v-i - »§ R? ~w~~~~~~~¢~@ ¢¢¢¢¢¢w# ¢?¢¢@w#www¢?@w ¢¢??¢¢@? 8'1 Hooaoooo NHHwn-uwv-n-enfiu-woe NFn-nMQOQQ J ' d M W q QQWW O Y 9? 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T$?TT?T????¥ @¢v¢?%w¢ ??wvv¢w¢¢¢?w.. @¢??¢¢w@ k & meflcefloficcno NHMmOQOO wv~NQHHoomeeoo HuMuu°¢¢ ~ . _ ifi w l‘ QHQQQOOL‘ q; |_~¢q-,gq|_~|;..qo|_~. QQQQQQOOQmOIrOOD-lr OOOGv-idi P05 1g fiwoomfi m v-w v-ev-a r-(v-lv-lr-i v-u-av-e - >- nf, , . _ . . ._-"_w w ,. . .‘ .. --@m»>w'.'.-g- >' °>u§u ,3? zs§a%§€§§€55 5§€g?§%s afieéfizgfisfisswfi ~a§;;§~= mi zmwQknwww-nwna wEww..-. “nannnnm ..¢.»..'~’~-.~~-~- '~ ~ P- “ Hfioq aqgqM SW3 8mm lCalculated to the nearest 0.5 ounce 3A1] nhnnam mm-Imd with Qn uni-prim}: warn flm-ivnd hv nuhtrnctino weirzhts taken in different half 0f the day. 46 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION NS. m5 mo fin: NAAPAQPAAA. . NANA NAJMANN? MAAwuOdHA-Qfiw A3 wwfinow 0.33 xmmnoumd in :33 woxaofi Nouiwso :4... UOAAAAO m-O HmOHQUAM 0S0 OH wwAwAAABQOA _ _ A _ . _ + _ H _ + Ni. NAi. NAi. N-N NA-N N-N N-N NAi. _ N-N NA.N Si. - - I I _ _ + + I NAAi. Si. N-N S-N NNA-.. NAA N-N N-N _ Ni. AAA A-N A. N .3 W“ iA.iW __ mfi __ w“. __ H + H WA NNWIA N-A N-.. Si. 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ANAAAANM NAAAANAASAA >4 Nfiwm AwAoH _ NAAAANM Nmwflwdkus who-flu.» uiuamzou mo QAAQAN 2AA AAA AAouEAAAo 5313s AaA-AJZASAA no Siam. 6A o-nem. . 47 Saw 05 u. 2w: 3020.32. 2... :0 v2.3 5:203 uezfibnu. .3 Eh... 020B xmiouma cu 52B @3222: 3.2.0.20 =<. Q0550 m6 30.202. OJ...» On wwuwgofiwnf. VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN + I + 2-.. .222 2-2 $2-. .-..2 .2-. 2-2 w. _ . - - . + + I m. .2-... .2-.. - - - - ._ - 2.. .2 . 2-.. .2-. .-. . 22 .3. .2 .... . w . w ... . 2 . 2. . . _ .2 . .22 . . .2-. .2-. ..2 h... 82 ... I I I .22-. ..-. W. .2-. - - - - - - - . I I I 2-. .2-.. .22-. .22. .3 i». ..2.-: ..2.-.2. W... .2.-” m. 22-.. w .22.. .2. .... I I I .2-. W. .22-. ..-. .22 .2 2-.. .1. _ 22-2 .2 2-. .-.. ..-. ..2.-M.. MW.“ M. “w... M I I I ex mm...“ 3a W. wn. 2H2 .H.2 .2.. 2H. .-. 2.. i. 2.. Y. .2 . .5. ... 2m ... . f. .2 .2. S. .2_.2. .2 .2 .- - . 1 I + I mm .22-. .......-. .2 T. .2 .-.. w. _ 2-2 .-2 .2 .2.. .-. i. N...“ k Wm o I I I - 2-. . -. .2- - - - - - - . . . 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I I .8. a... .80 >..z .30 A... .23.. .22.. a m. 40H. 2.5m 2.05 25h dnow .205 umah E... owQ >02 .00 3% 2&4. .205 duh .58.» .3005 NO M a s 0 50M m0 w... om02w>w .00 .04 00h .30 .22.... 00.2 50h 6M4 5am .0 m m m n m I . no 202.20.22.55 2050M 2x255 .>< mfiww 130m. 332x22... c. fi%.mmms2.w_awm.m%..2fim.nm 0.08.5.5 P m. . . 0.35am 2:30:00 we Q5028 02$ E noawflso 0.50.. 1.01.315 m0 230$ .5 030a. 48 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION cw H HH NH __ H HN _ H. H. NN m NN fiom __ NH H H.H N H. NH N H. mH H HH min. _ Hzwwz w o v oH _ H a H. o oH v HHH mmom fl mH k H H.H 1 HH F H. wH M H.H H wH H. NN HHHomH _ _ _ w _ H _ H. _ H. _ H. _ H. _ m H. H. m H; mHHHw _ HHNExQHHH H __ H. __ H. __ m __ H. __ H. H H. H H. H 3 28m __ _ HE H H 5 h H“ H. HH. _ H H mm mH NH. 50m _ H _ HH _ H. HN _ H H. HN _ H H. HH N NN 2H6 _ wag? NH W H H: v N _ H. H.N _ H. H NH N H.N wém _ HoEEHHw uHHHHHHm wHH..H.HHHw E wcHHHHm :3 4H3 HHfiH :3 =3 HHFH HEQ uHHHHHHm HwHHvo HEHHH _ H55 Hana». can» H55 HHNHHHB 52$ n93 52H H55 HwHHHEHHw $2 _ .8395 HwEHHHHHw mwmH HoHxoHm uHHHHQw $2 HwHnoHu 67H Hwfiwonw HHwnH .3865 A HwHHHHHHHHw HoEHHHHHw MQEFHHHW wHHHHHHm uHHHHQw HaHPH. Mww 33H WQHWHHFHQO mflowdwm HHH mwmmu Ho dZ an 55.5. wuucmau eflflam-HOU oi w: 5am w: mQ-FH OMGMQ>Q Hu-Howaom we iémmhdn-EGQ 6H 02am. VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 49 ships of the average monthly gains for each child are summarized in Table 18. They form the basis for arranging the curves of growth, one for each individual record, in Figures 11, 12, 13,14, 15, and 16. Those records in which the average monthly gain in the fall months exceeded that of both spring and summer months occupy the lower portion of the figure; those in which either spring or summer, or both, exceeded FALL RATE LES3 HAN THAT OF SPRING OR (AND) SUMMER ‘EIGHT Ill POIIIDS FALL mm: GREATER mm THAT 0F SPRING AND GREATER mm THAT or summ IIIGI‘! IIPOIIDS Fig. 11. Curves of growth, during 12 months, of individual white boys who were constant gainers. Case number at end of curve. the fall rate are in the upper portion of the figure. According to the records in Table 18, a little more than 1/2 of both .the white and Mexican children, and 2/3 of the negro, grew faster in the fall than in either spring or summer. About 1/3 of the white and Mexican children and nearly Z4; of the negro children had greater gains in spring than in fall. 50 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION FALL RATE LESS THAN THAT 0F SPRING 0R (AID SUMMER HEIGHT II POIIDB FALL RATE GREATER THAN THAT 0F SPRING AND GREATER THAN THAT 0F SUMMER WEIGHT IN POIIIDS Fig. 12. Curves of growth, during 12 months, of individual white gifls who were constant gainers. Case number at end of curve. VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 51 One white child, 10 Mexican children, and 6 negro children (about 1/3 and % respectively of the two latter groups) made greater gain in summer than in fall. Summer rates exceeded spring rates more often among negro and Mexican children (in almost 1/2 of the cases) than FALL RATE LESS THAN THAT 0F SPRING 0R (AND) SUIMER WRIGHT II POUIB FALL RATE GREATER THAN THAT 0F SPRING AND GREATER THAN THAT OF SUMMER IBIGH‘! II POIIDS Fig. 13. Curves of growth, during 12 months, of individual Mexican boys who were constant gainers. Case number at end of curve. among white children, who had only 4 such cases. It is clear from the course of growth disclosed by these individual records that while fall is an outstanding season for good gains, neither spring nor summer is incom- patible with excellent growth, especially among Mexican and negro children. 52- BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION The weights of these 98 children at the first weighing in the record year ranged from 39 to 105 pounds. Direct comparison of the monthly per- centage rate of gain in weight of these individuals is made possible by the use 0f a semi-logarithmic_ scale to plot the individual curves of growth (8). Regardless of the initial Weight, parallel lines represent FALL RATE LESS THAN THAT OF SPRING OR (AND) SUMMER WEIGHT Ill POIIIDS FALL RATE GREATER THAN THAT 0F SPRING AND GREATER THAN THAT 0F SUMMER WEIGHT Ill POUNDS Fig. 14. Curves of growth, during 12 months, of individual Mexican girls who were constant gainers. Case number at end of curve. the same percentage rate of growth, and in all cases the steeper the line, the faster the rate. The dotted line connecting the last spring month weighing with that of the first fall month (Figures 11, 12, 13, 14, 15, and 16) represents the average rate of growth through the summer, without conveying any information as to change in weight from one month to the next in summer. Whether any child lost weight in one or more IIIGI! II POUN HEIGHT II POW“ VARIATIONS OF GROWTH IN. WEIGHT AND HEIGHT OF CHILDREN 53 summer months is not known since no weights Were taken in summer; but any summer time losses were compensated by gains before the first fall weighing. The most conspicuous feature of the individual monthly FALL RATE LESS THAN THAT 0F SPRING OR (AND) SUMMER FALL RATE GREATER-THAI 111A‘! OF SPRIIG AID SHELTER THAI ‘HAT OF SUMMER Fig. 15. Curves of growth, during 12 months, of individual negro boys who were constant gainers. Case number at end of curve. - gains as brought out in these graphs is the variation in the amount of any one child’s gain from month to month and the infrequency of approxi- mately uniform gain for even two consecutive months. Among the 98 records there are only 5 in which the gains of three consecutive months 54 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION were within 3 ounces or less of each other; in 43 of the 98 records the gains of no more than two consecutive months were Within 3 ounces of each other. The months in which these individual children made their FALL RATE LESS THAI THAT 0F SPRING 0R (AND) SUMMER FALL RATE GREATER THAN THAT OF SPRING AND GREATER THAN THAT OF SUMMER WEIGHT m POINDS Fig. 16. Curves of growth, during 12 months, of individual negro girls who were constant gainers. Case number at end of curve. maximum and also their minimum gains are recorded in Table 19. Septem- ber is the only month of the nine in the schedule of Weighing in which neither maximum nor minimum weight appears; in each other month both 55 VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN .§ wuMHaE 02w JQ-MOE HQSQOGQ 5m UOQNOZQUU mm i wwxnwfi WJHGOE 0S0 Gm 5am USE; N N N _ N _ H. HH H. N N N _ N _ H N H. NN 5am H H. ..N N H H N N N H. H. H NN H. H.H NEH. HzNwz N H. H H N N H N N H {m H ifi ...H. H.H Ném N N N H N H. N N N N N N N N NN HHHQHH N N H. H N N H N N H ... H. H. N ... N H.H NEH. HHHHNHNNE H. 4% ifi H. H. H. N 3 ..N N ..N .. N ... H H ..N H.H NNQNH N H. N H. NH N N H.H N H. H. N N N NH. HHBNH N N ..N N n. N N N H. N H. H. N ..H. NN NHNHu BEN» L. H .3. *m aw aw 2N _ N N N N N H __ N H.N NNQNH l _ + I- _ + l _ + _ l _ + _ .l _ + _ l _ + _ l _ + I- _ + 8 H8 . ¢ . - u ¢ - . m 5H. 8a .52 _ to _ Hnwm _ .54 _ .52 pom NH. dz 5N 83H :39? SMQOS 23 H: wwFHHHooo E528 11.. H.305 5am NNHHQH HEN. CHEER. +. 5am Nmoi on..- HHSH?» MOM HHwHwHHHHu mo dZ Cm 55am. mac-Sam 323.230 on»? HEB concise we 5am EHHENEE was EBEwKH-H no mn-HGO: .2 Sana. 56 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION maximum and minimum gains were made, and frequently identical gains were made by the same child in two different months. Approximately 1/3 of the maximum gains for the white and Mexican children and 1/4 of them for the negro children were in the three spring months, February, March, and April. Among fall months, maximum gains were made in October, December, and January with nearly equal frequency, with November showing fewer maximum gains. The minimum gains were about equally divided between the three spring months and the four fall months. April for white children, and March for negro children, stand out as months of minimum gains, with other spring and the fall months fairly comparable in number of minimum gains. Both March and April show more minimum gains than February among Mexican children, but No- vember and December have still greater numbers of the Mexicans’ minimum gains. While approximately two-thirds of these individual records lend confirma- tion to the trends in seasonal variation in growth indicated in the fore- going analyses of data for groups A, A+B, and A+C, there are plenty of departures in the individual records from the group trends to emphasize the necessity or regarding each child individually in following his course of growth. It is apparent from the findings upon the individual records in this study that if a natural biological phenomenon tends to express itself in rhythmic seasonal variation, the rhythm is not uniform for all individuals of any of the three races living in the same city and observed at the same time, or else this natural tendency is over-balanced at one season or another by one or more other factors influencing the course of growth. An inquiry should be made into the probable reason for a child’s failure to gain in any season of the year. How much irregularity in the monthly rate of increase in weight is within the zone of normal growth must be determined by further study. Diet The analyses using diet records were referred in particular to October and April since these were outstanding and contrasting months with respect to the gains made in them by the various groups. The use for each child of but one diet record of date as near as possible to the weighing intervals under consideration seemed reasonable. In another study (26) as well as in this, striking similarity has been found in the kinds of foods eaten at the different seasons of the year by school children of the three races. The diet scores ranged from 63 to 66 (on a basis of 100) for January, February, March, and April 1929‘on the diet records collected from all the white children in this study that year. The records secured from a sufficiently large number of pupils in any one month may be accepted as a fairly satisfactory indication of the customary type of diet. The number of diet records available for this analysis were in May and October 1929 and May and October 1930 for white children, 136, 124, 117, 41; for Mexican, 90, 90, 65, 35; for negro, 186, 191, 124, 44. The diet VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 5'7 records of each month used were divided into two groups according to whether the children for whom they were secured gained or lost weight in the corresponding month. Only nine groups of gainers and losers could be formed for each race owing to the small number of children in October 1930, among whom there were but 4, 3, and 7 white, Mexican, and negro children, respectively, who lost Weight during this month. The analysis made of the diet records was similar to that employed in a previous study (26) in which the same type of record was kept. The prominence in the diet of milk, butter, fruits, vegetables, protein-rich foods (other than milk) and sweet foods, was judged by the frequency with which they were recorded in each child’s records. Such procedure is regarded as indicating with a fairly high degree of reliability the kind of foods constituting the diet, but as giving only suggestive rather than definite information as to the amount of the several foods consumed. However, whatever error is involved in the diet record analysis applies alike to those of the children who gained and those who lost weight. Only one of the nine groups of gainers and losers (the Mexican children in May 1929) gave evidence that the losers had a poorer diet than the gainers, and this in reference to but one food; '71 per cent of the losers had l/é cup or less of milk, while of the" gainers only 54 per cent had such a small amount. Otherwise, gainers and losers for each set of diet records appeared to be remarkably similar with respect to the character of their diet. The May and October diets of the gainers and of the losers were also compared. Noteworthy differences which suggest a positive relation of type of diet to gaining were observed only with some of the food classes for the Mexican children who were gainers. The percentages of the gaining group having 1 pint or more of milk in the Octobers were 39 and 47 compared with 20 and 30 in May of the same year; in October 1929, 35 per cent had more than 1/3 serving of butter per day, while in May there were only 20 per cent with this much; in October 1930, 69 per cent of the gainers had 3 or more servings of cereal foods of all kinds, while only 33 per cent in May had the same amount. The data of this study therefore appear to give no convincing evidence that the character of the diet was an important factor in effecting the relatively large gains in October and relatively small gains in April. The fact that information as to the amount of food eaten is lacking may be in part responsible for the fact that no positive relationship was found. Yet it is also possible that some other factor (or factors) may have overbalanced the effect of diet. Minor Illnesses Mention has been made of the elimination from the children’s records used for this report of all those in which Weight for any child was less than the preceding weight, if the child reported a major illness within the interval between weighings. That there was no necessity to include “colds” among the major illnesses can be seen readily by the figures in Table 20 58. ‘ BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION m6 6. N.N" m 6.8. Na m. m.» "" "iwN N". ".66 6S mm" duO 6mm" N.N" a ".w w ".6". m... w". ".6 "" 6"" m" ".6". co" 62 5&4 6mm" "..". v mam m" 9mm m» Nu m."" w" 6.2 3 Ndm 3 mm" JQO $3 _ @562 N." " ".". w m... ". 3w o". 3 w."" w" w... 6 2w 3 6"" 5&4 mum" _ "."." N m.".N m ".8 "" w" m6" w" "iw" wN "."". mo" Nu" doO 6mm" ".." " 6.3 "" m6 m N."". v N". .5 m6" "" m6 6. ".3 2. mo" QQ< 6mm" ".6" m “.3 6. Q6". "N wN ".."" ".." m6" 6N mi. mo" m3 .600 6N6" awocnza m6" w w.N N Q2. 3 E ".6 w m." 6. Q2. m". .6 E3 32 6.2 w ".3 N." W8. 3 S 9m "" >3 8 "=2. "."" 62 J00 62: m6 m ".NN b" v.2. n» b". ma. "" 6.3 w" “.3 "b 3 §Q< $3 "."." m 33 6 6.3 m." ".N m6" w" a...» mm w."m w". Nm" .600 6N6" w££>> 6.3 c" mdN ".." Ném um .6 m6 " N.m 6 ".."N mN Nd". mm m"" ..fl"< 6N6" w". 6.7.: =6 6Z_ a". _ 6Z_ 66 _ 62 @236 o". _ 6Z _ 66 62 .6 62 o". 62 3W8 "Z663 oZ _ .650 _ E60 _ 282 62 vacuum oZ _ .650 _ 360 2S2 6v" w:u".uwm..% Emma..." . maofinw w". 06.6"" £6.55 ":5 .33" 3E0 us» 3 3.2663 ma MEJMEB 361.95 005m $.25" JHGQQH £5 MGM 1on5 0H0; nvuooou NGmJUmQbP onc-"B Gouwi-"o 0": M O @3565 G "Ea M-hmhfim oluuanomounou G HO% "icuou p-zflfimfi .¢N 01-85 VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 59 which show the health record secured from the children for the two months used in this analysis. For the most part, quite similar percentages of the gainers and losers within each race had suffered colds in the same month. Colds were reported by from 21 per cent to 39 per cent of the white children, by from 3 per cent to 29 per cent of the Mexican, and by from 8 per cent to 32 per cent of the negro. The only noteworthy differences are with the negroes, in October 1930, when more gainers than losers had colds, and with the Mexicans in October 1930, when more losers than gainers had colds. ‘The percentage of gainers and losers in each race reporting “no illness” were likewise fairly similar in a given month, ranging from 48 per cent to 72 per cent for white, from 61 per cent to 88 per cent for Mexican, and from 56 per cent to 83 per cent for negro children. Ailments other than colds as reported by the children included tonsilitis, sore throat, earache, ear infection, toothache, headache, stomachache, “sores” (usually impetigo or scabies), sore eyes, rash, “fever,” pyelitis, measles, and mumps. It must be remembered that such diseases as pyelitis, measles, and mumps among these other ailments in these records were never associated with a loss shown on the child’s record; any loss accompanying them had been compensated by the time the child was weighed at the time he reported the illness. Some 5 to 10 per cent in each race gave report of one or another of these other illnesses each month. In every case among both gainers and losers the percentage of children who had had colds during the month was less in April than in October of the same year. This lesser prevalence of colds in April associated with consistently poor gains, and greater prevalence of colds in October along with uniformly excellent gains is not concordant with the suggestion of Emerson (7) that lesser gains found frequently in spring are in large part a reflection of the influence of respiratory infections. This study appears to afford no evidence that colds or other minor ailments have a determining influence upon the seasonal variations in growth. Climatic Conditions The meteorological monthly and yearly summaries for 1929, 1930, and 1931 secured from the U. S. Weather Bureau in San Antonio have been inspected to see if climatic conditions might bear an obvious relation to seasonal variations in weight gains. The climatic conditions during the time in- cluded in the period of data collection and considered in this connection are recorded in Table 21. The deviations from normal of monthly mean temperature, and of rainfall, together with the maximum, minimum, and daily range of temperature for each month, range of mean atmospheric pressure, relative humidity, and percentage of sunshine, are of such an order as not to mark any one year or season in the 21é-year period as being exceptional. The two months, April and October, that command particular attention with respect to gains in weight, hold a fairly middle position among the other months of the year, neither being at the extremes of climatic conditions. It is especially interesting that these two months v so BULLETIN N0. 51o, TEXAS AGRICULTURAL EXPERIMENT STATION cc wc cc ww wHcm cccw c.cc _ c.cc c.cc _ Hw:.:=4 cc cc wc cw ww.H.l 3.” .cc.H cccm c.m| H.cc c.cc c.cc c.ww c cc wc cc 3S wc Hc wc cw :27. cH.c wmw mccc c.w|. H.cc mwc c.wc c.cc c cw Nw ww 5&4 . wc cw cw wc ~a¢+ ww.H ccd Hccm w.w|. wdc c.wc c.cw c.cc NH cm ac ww n55 HwcH cc cc wc ww 22+ cc.H wcd mccc 3+ w.cc w.cc c.cw w.cc c wm cw cc éwh cc cc cc cc cw.w+ cw.H cw.c wHcc 2+ c.cc c.cc H.cw c.cc c cw cc cc .52. Hc cc cc cw wHcm ccww c.ww c.wc c.cc 12534 cc wc cc wc wccl Hc.H ww.c cHcc cal c.cc c.Hc c.ww c.cc c cm cw cc ..uwQ . cc mc cc cc cc.c+ cc.H ccw HHcc cc‘ c.cc c.cc c.cc w.cc c cw w» cw >oZ cw wc ac Hw wc.H+ cud Hc.w cccm c.c|| c.cc w.cc c.Hc c.wc c cm cw cc .30 cc cw cc ww $.71 ccw wc.H Hccw 5+ c.cc c.cw w.cc c.Hc w ww wc ccH scum cc cw cw cw Sal mwd Hw.c cccw 2+ c.ww c.cc c.wc c.cc cH ww cc wcH cs4 Hc cw ww ww wH.c| cH.c cc.H cccm w.c+ www c.ww c.cc c.cc wH cm cc cc 35c cccH Hc cc cc Hw cc.H+ cww ccw cccm w.H.l c.Hw c.cc w.cc w.ww c cw cc wc 25H. cw cc cc cw Hwdl. cmw cw.c mccw H.c|. H.cc c.cc c.cc c.ww c wm wc Hc .32 cw mc cw Hw cc.cl| cH.c cud cccw H.c+ H.cc c.cc c.Hc c.cc c wc cc cc v54 cw cc ac wc wc.c|| ww.H cc.H cccc c.w|l wdc w.wc c.ww w.wc w N.“ cc Hc 5x5 wc wc cc aw Hc.c|l cc.H wc.c cccc ~c+ w.cc c.Hc c.Hc c.Hc c cc cw cw 59H cc wc wc cw Hwcl. cw.H £4 8.3 H.c| c.cc w? c.ww c.cc c cm HH wc duh. $ wc wc cw wHcu wwcm c.cc c.wc c.cc H5154 cc wc wc cc cw.c+ Hc.H wcw wHcc c.c+. c.cc c.wc c.ww c.wc w cw Hm cw .25 ww mc cc wc cm.H+ cc.H cH.c wHcc w.c| c.cc c.cc wcw c.wc w cc Hm ww >02 wc Hc ww ww cccla mm.“ cc.H cccc c.H+ c.cc c.cc c.Hc www c Hm cw cc duO cc . cw cw ww wcHl. £3 wcw 23 3+ c.cc c.cw w.cc w.cc cH cm Hc cc flow cw cw ww cw Hw.ml| mg Hc.c cccw c.H+. c.ww H.cw w.wc w.cc cH cw 2.. cc $54 cc cc cc Hc Hw.c+. cH.c wcd wccm c.H|| w.cw c.Hw c.cc c.cc cH mm wc cc .33. cmcH wc cc wc cw cmcl. cww cH.c 8.2 c.c.._.. c.Hw c.Hw c.cc H.Hc wH cw cc cc 25H. cc cc cc cw wc.w+ 3.» cc.c cccm w.c|| H.cc c.wc c.wc c.ww cH ww ww cc >uH>H cc cc cc ww mwcl. cH.c cad cwcm c.w+ H.cc wdc c.cc c.Hw HH cm cc wc v54 cc cw wc Hw wu.H+ ww.H cH.c Hccm c.c+ wdc c.cc c.cc c.cc c cw wc wc .35 cc cc Hc ww cw.Hrl cc.H cH.c wccw w.c|. w.cc c.cc c.cc c.cc c cw Nu wc 59m Hc cc cc Hw cc.c+. cw.H Hc.c cccw c.H+ c.cc c.cc c.ww c.cc c cw ww cw d2. . . . . Haiaoc .m> . 38.3: .w> . . paw E a nooZ E u Accofi m3..- mo mmsofi sunoi m5» co cwoSH E2 xmwm cmdoA Lcwwaw . c c Hlnv hunonzwoc HwEaoZ 130m. 6.5m Tnciocowufioc Hug E5 fiwSH ciao non no TI mmwmxmH umona no Iucmwowwo LQZ 5.55 2.3.3 35w $4 cwoz omnwa 33D 50:02 Hum? wzmnmnsm wuscnwoawn lmofiuw . mficmfids mosaic flsown 03px?» .562 Eomcwfinmowam "zonnuuswh mowuwww 5 QHHHuQ-HOQEQ-H. QGNQH QHGQHHHQ Him QBIOHH" H0560? um n: HO IQHOOOH 52H SCAM ‘MN 02GB VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 61 which show the most marked differences in the average gains in the several groups of children should, with the exception of two adjacent months in each year, have the least difference of any two months of the year in their mean temperature. In 1929 April and October mean temperatures differed by 0.8° F., June and July by 0.2° F.; in 1930 the April mean temperature was 2.4° F. higher than the mean temperature of October, and July and August differed by 1.6° F. The maximum temperature of April was 3° F. lower than that of October in 1929, and 3° F. higher in 1930. The minimum temperatures of April and October differed less than the minimum temperature of either month differed from that of the month preceding or following. The highest and lowest daily temperature range in October and in April are. not unusual in comparison with the other months. There was an annual average of 62 per cent of sunshine in 1929, which was a little higher than that in 1930, with an average of 51 per cent. The relative percentages of sunshine in April and October were reversed in the two years, April having had 50 per cent and October 68 per cent in 1929, while in 1930 April had 49 per cent and October 40 per cent. September, which in its mean temperature more nearly resembled sum- mer months than fall months, was found to be almost as good for gaining as October. Both March and April had distinctly higher mean temper- atures than the four coldest months, November, December, January, and February, but they were also distinctly cooler than the summer months; yet in the several groups of the three races otherwise unclassified (Table 3), April consistently and March usually had a smaller proportion of the yearly gain than the average monthly gain of the five summer months. If high temperatures were incompatible with rapid gains, and the effect immediately apparent, September would scarcely be expected to have taken a place beside October in good gains, and March and April with inter- mediate temperatures would scarcely have occupied the lowest position in the scale of average gains. The intermediate and similar temperatures for April and October are associated with the average monthly gains show- ing the greatest differences. It might be possible that there is a cumulative effect of the summer conditions really favorable to growth that finds expression only near the end of summer, and similarly that less favorable conditions in fall and winter months find expression in the lower net gains of March and April. Another possibility is that the varying period of daylight may have had an influence upon the course of growth through the year. In some animals, for example the Angora goat and the Shropshire sheep, the estrus cycles occur only in the season of short days. On the basis of the newer knowl- edge of the internal secretions of the anterior pituitary, it is almost certain that the sex cycles are controlled by these internal secretions. There is some evidence that the activity of the pituitary is correlated with the season. As a growth-promoting hormone is also elaborated in the anterior lobe of the pituitary of mammals, it seems reasonable that a possibly increased production of the growth hormone might effect a 62. BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION greater stimulus to growth in the fall months when days are growing shorter, than in the spring and summer with lengthening days. April and October each follow the month in which equal days and nights occur, but differ in that April is in the period of lengthening days while October is in that of shortening days. The relatively smaller average monthly percentage of the yearly gain made, especially by white children, in the summer months when days are longer, is concordant with the finding of Nylin (15) that artificial irradiation retarded weight increase. On the other hand, some groups in this Texas study had gains in March, _ February, and November no greater than the average monthly gain in summer. In view of the monthly weight changes made by individual children in this study, the suggestion that cumulative seasonal effect or length of day influences seasonal variation in weight increments seems hardly as feas- ible as that some other factors than climatic conditions per se are chiefly responsible for the contrast in average net gains of April and October. Further, it must be recalled that among the children whose records of growth through the year were examined individually nearly lé of the Mexicans and negroes and a few of the white children made good gains during the summer. N0 explanation of seasonal variations in average weight gains was found in the climatic conditions. Other Possible Factors Among the factors which may have a share in determining seasonal variations but upon which this study contains no data are the amount of exercise; the amount of daily rest, particularly hours in bed; the quantity of food eaten; and the nervous tension from home life or school program under which the child may live. The speculation is made that with the opening of schools in the fall the majority of children return to a more regular regime of living with perhaps more rest and more regular meals than they had in the summer. Such a suggestion implies that con- ditions of rest and exercise in relation to food intake were better attuned to the processes of growth for Mexicans and negroes in the summer than for white children since the latter had a poorer growth in summer than did the other two races. Another speculation offered is that the strain of the special events (final examinations, plays, and pageants) that usually come at the last of the school year, in addition to regular school work may so interfere with food intake and rest that rate of growth is re- tarded. Definite information along such lines might help to explain both the trend of seasonal variation in groups of children, and the varia- tions in seasonal differences in growth rates of individual healthy children. GROWTH IN HEIGHT Selection of Records The schedule of measuring periods (Table 1) included five in which standing and sitting heights were measured, the intervals of growth in VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 63 height affording a series of fall-to-spring and spring-to-fall increments. The approximate length of the four intervals between measuring periods from the beginning to the end of the time of data collection was for white children 8% months, 5 months, 7 months, and 7 months; for Mexican children 81/2, 5, 7, and 6 months; and for negro children 9%, 5, 7, and 6 months. Ideally, all height measurements of a given child should have been made at the same time of day. This, however, was not practicable in all cases owing (1) to the promotion of the child through the grades, which sometimes made it necessary to change the measuring time for a class to fit this Work into the regular school schedule, and (2) to the necessity of measuring height and weight in the same Weighing period. In the interest of accuracy with the available data, the records selected for this analysis were limited to those of children measured in the same quarter of the school day. On this basis, two groups of children were formed for each race (Table 2). , In group A were all children (72 white, 35 Mexican, 158 negro) who had been measured at the same time of day in all five measuring periods. Group B consisted of the largest possible number of children (white 176, Mexican 118, and negro 288) that would afford a comparison of growth made in two periods, fall-to- spring and spring-to-fall consecutively, and also permitted direct com- parison of the three races because the growing interval was the same, October 1929 to March 1930, 5 months, and March 1930 to October 1930, 7 months. Seasonal Variation by Race and Sex The average gain per child for both standing and sitting height for the fall-to-spring and spring-to-fall intervals was determined by dividing the total gain of the group by the number in it. The average gain per child per month was then derived by dividing the average gain of each interval by the number of months in the interval. Thus comparable average monthly rates for any two adjacent intervals were secured. So as to compare seasonal variation in height with that in weight, the average gain in pounds per child per month for the same periods was also similarly calcu- lated. These data for the sexes together and separately in each race are given in Tables 22 and 23 for groups A and B respectively. Group A, Having Gain of Two Years With the smaller group of children (group A) followed over the longer period of time, three consecutive spring-to-fall :fall-to-spring intervals are available for comparison with each other. In Table 22 are recorded the average gains in standing height, in sitting height, and in weight for these four consecutive ‘intervals of time. Differences between seasons in average monthly rates of growth in standing height are seen to be quite small and not consistent among the three races, nor within the Mexican and negro races. For white children, spring-to-fall rates were less than fall-to-spring rates; Mexicans gained less in two spring-to-fall intervals and more in the third than in the adjacent fall-to-spring inter- val; negroes had greater gains in two spring-to-fall than in fall-to-spring 64 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION 6E d dnmo: and flwomxwdm “.05 v iondmso 33>?“ 32w .952 u § éwocaz 12a $3 .=9§E@ wank; _ _ _ E... mod 2.6 mwd $3. _ $3. dfid _ uwdd 9:... EAd mSd Hwfid m3 _ 5cm 2.... 8a 5d mdd mvdd _ vddd ~25 _ mwdd 22a 54d dwfid did ww i wEw ouwoZ 5.... dwd E... mdd dwdd a dvdd m2... A $3. ddHd 2:... m2... in... 2. Rom mad 5d 2.... find dddd _ wvdd mwdd _ 3.3. ddud wdfid did 2:... mm 5am dad 2.... End and wwdd 53. dddd _ dwdd did dud E3. 2.2. dm 3.50 $682 :2 mud 8d 2.... uddd Hddd N8... __ dddd 2N5 m3... $2. 55d B _ gem End dud mud 3... 23. _ vwdd Edd _ 3.3 53d mNAd 3:... $2. m». A 5cm mwd $5 Hwd and 53. vdHd dwdd wgs ddmd “is N25 £3 mu 2.20 8E3 id 5d ddd £3 mwdd _ Edd 2.3. _ dddd did 2:... $2. 3.2. g __ 98m _ n65 05d .05 N. 6E m ~65 d-w “.08 Tm 6E N. .05 m H65 d-w ~65 7d 6E v 6E. m ~65 d-w B. 2x5 3. J00 d». v32 3. do0 5. zwi dm. .30 dm. n32 3. .30 3. ~32 8. .30 d». n33 2. J00 .8. .30 -3. 5&3 -2. .30 ‘d? duh 5m. .30 -3. n32 dm. .30 an. 5mm dd. .30 udm. 03E .3. .30 -3. duh > woman . , mo Mum v0.3a mwcwom Jswmokw moses“ .330: Mcwxmm museum Jnmmmn Mimwnwdw .oZ £205 nwq 3E0 nwm 5am wmw$>< 253w was no.3» o5 u: 2.5M 0-3 us: mac: on» .3 mdfiruofi: QPfl-UOOwGQQ 53m n9»: “sumo? via .33»: M533 Gamma: Mimwiadm E midw .3 G305» ma awkoufi du 01-69 VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 65 intervals and equal gains in the third set of adjacent seasonal intervals. Seasonal differences in average monthly gains per child in sitting height are in the same direction among Mexican and negro children, spring-to- fall rates being less than fall-to-spring rates in all six comparisons. For white children the spring-to-fall rate is less once, but more twice, than in the adjacent fall-to-spring interval. Within each race the seasonal differences in average sitting height gains are usually, but not always, in the same direction as are those for standing height gains. Boys and girls in the three races had seasonal differences in standing and sitting height gains that usually agreed with those of the correspond- ing total race group, but some irregularities are exhibited. These small differences in height gains, variable among the races and Within them, show no tendency to a definite seasonal variation of growth in height. In contrast to the variable seasonal differences in height gains, the changes in weight over the same intervals were consistently more in fall-to-spring than in spring-to-fall among all race and sex groups. Group B, Having Gain of One Year The yearly gain in height was practically the same for the three races— standing height 2.1 inches, sitting height approximately 1.0 inch (Table 23). In each race, differences in average monthly increases in height dur- ing the 2 intervals were exceedingly small, unworthy, no doubt, of serious consideration, but it is interesting that without exception fall-to-spring average monthly gains tended to be less than spring-to-fall gains. Seasonal differences in gains in weight over the same periods are probably large enough to represent a real difference in growth rate, with fall-to-spring increments exceeding those of spring-to-fall, just opposite in direction to seasonal differences in rates of growth in height. The differences in seasonal rates of increase in standing height for the sexes separately in group B are in the same direction as for both sexes of Mexican and negro children, but the white boys’ rate in fall-to-spring very slightly exceeded that of their spring-to-fall rate, the reverse of the seasonal relationship for the total group of white children. In sitting height gains, the seasonal differences were not consistent for the three race groups, the white children showing a little higher rate in spring-to-fall than in fall-to-spring, while with the Mexican and negro races the fall-to-spring rate was the higher. Growth rates in sitting height were more variable as between boys and girls than were standing height rates. The inconsistency in seasonal differences in average monthly rates of growth in height may be due to the very small numbers in the respective groups; yet it is also possible that seasonal differences in average monthly rate of growth in height may vary from year to year. But with seasonal differences of growth in height as small as in these data it seems more likely that among these children growth in height through the year was relatively more uniform than weight, or else marked differences may have been confined to shorter time intervals than those used in this study. 66 _ _ _ _ _ - NN... _ m... 3... _ N3.N N...N $6 03.... N...... é .5... _ N... NN. _ 33... N3... NN... ....N NNN .03. 33.N _ .3... 3... _ 3N NN... N... _ N....... .5... _ NN... _ ...... N... _ ........ 3... _ N3... N... 3... 2...... 8002 3... L NN... 3... L NN.N NNN .5... _ .3..... 2.... __ N3... __ N... NN. _ 2.... . ........ t .2... .N.N .3 wém 3... _ .3... N3... _ NN.N NNN NN... N3.... NN.... _ 3.... _ 3.... NN. N3... 3.... _ 3N... N..N N.. .80 .....N _ ..N... NN... _ S... 3.... i... .2... N9... _ N... _ N... NN.. NN... .3... _ 3N... N..N 3.. Ni... .5026... ....N i 3... N..... j N...N NN.3 ....... 5.... ..N..... N... t ..N... NN.. .3... 3.... ¢ NN... ....N NN .080 3...N .5... N0... NNN 3... N... ......... N3..... t NN... _ N... NN. ..N.... 3.... NN... ....N 3. 5cm NNN _ NN... N0... _ ......N N... N3... .5... NN..... _ s... _ 3.. 0N. 2.... N3... NN... ..N.N .3 N50 0......» ..N.N . N... S... _ .N.N NN... 3... ..N..... 3.... __ 3N... L N..... N... _ N3... N3... _ 3N... N...N N... Ném :30? :35... 5.55 55H .0009 :35... 5.55 150B 130B :35... :35... $0.0m. .50.. .>< n00 $4 om. .000 5Q $4 5Q $4 om. .000 5Q $4 n00 54 om. .000 0:000... .3 N325... m AWN. 000 20.55 .3 0:020... m A“? 300 £3.55 3. @5005 m ém. .300 ..N. .30 ..N. 52>. .58. ..N. .80 ..N. 4...... .88. ..N. .30 ..N. .8... .38» 82s -..N. 5...... -..N. £0 -..N. 5.2 NN. 30 -..N. 52>. -..N. .30 0.. 5w 85. dz 2.5.0.. .3002, 5:05 .20.... $0.3m 3:3: 3:90: 0505.5 33:0 .2. 0mwn0>0 i500 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION 9.50am 000.. 000:0 0:0 m0 N15 0:: win who: 0:0 .3 m-s>u0aE Sau-cu-Mcmuam via .M.:unm-.5|=au 030500350 i: 0:55 0:90? win 3:30: M535 3:30: ufiwflfl-m Gm 950M .3 :30:m m0 :?$0uU 6N 050B VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 67 Such disagreement as has been found between the seasonal variation in height increases of Groups A and B of this study_ exists between the find- ings of other workers with school children» Nylin (15) reported maximum weight increase in the same season as minimum height increase, and Orr and Clark (16) found maximum weight increments in July-September fol- lowing maximum height increases in April-June; but Hitchings and Fitz (10) found that height increases were continuous through the year or that maximum rates of growth in height paralleled those of weight. Age Groups The children in group A of each sex in each race were divided into. subclasses according to year of age to determine what relation age might appear to have to seasonal variation in growth. The Mexican age groups were regarded unsuitable for this further analysis because only two age groups of the boys and two of the girls contained more than 10 individuals, the greatest number being 21. The average gains per child for the year and the average monthly gain in standing and sitting height made in spring-to-fall and fall-to-spring are shown in Table 24 for the several age groups of boys and girls in the white and negro races. Calculations were not made for groups of fewer than 10 individuals. The average monthly rates of gain in standing height for 4 of the 5 age groups of white girls and 1 of the 5 age groups of white boys, differed in the same direction as did the rates for the group of all ages. In the remaining 5 age groups the seasonal relations are reversed as compared with the all-ages group. Of 16 age groups of negro children, 4 of boys and 5 of girls show fall-to-spring rates less than spring-to-fall rates, thus resembling the group of all ages, while the remaining 7 age groups show an opposite seasonal relationship. The entire range of average monthly rates for white children is from 0.156 inch to 0.213 inch; for negroes 13 years of age and under, from 0.151 inch to 0.239 inch; for 14- and 15-year-old negroes, 0.050 to 0.076 inch. Any differences must be exceedingly small between spring-to-fall and fall-to-spring average monthly rates in a given age group and no definite and consistent sea- sonal variations among age groups are evident. Rates of gain in sitting height are in the main about one-half that of standing height, and irregularity in direction of seasonal differences is common. The seasonal differences in average monthly gains in weight are in favor of the fall-to-spring period, except for the 7-year-old white boys, the 10- and the 11-year-old negro girls, and the 11-year-old negro boys. On the whole, the analysis of the data for the several age groups throws no additional light upon the question of seasonal variation of growth in height considered either alone or in connection with gains in weight. as BULLETIN N0. 51o, TEXAS AGRICULTURAL EXPERIMENT STATION _ m S 5... mvd _ mod £3. wood ood owod omod .35 S 3 B... ood v _ o3 vmod wood mod mood ovod mvd B En omd SA mod x5e wood i2 Hmmd £2 :3 Hm 2 ov.o EA 3S $3. mid mmA 2:... $2. 3N 2 mfl 2.30 owd omd $3 mood 33d mmA £2 Emd 3a mm S“ wod mod 2w xx... oood Hm; mmmd $3. 3m 2 S 3d 3... mod ovo.o 33 ooA 2S. £2. mmm mm o 8.... mud omd omod o2... mod 2:... moHd 3m mm @ H o _ ouumZ w 2 mvd 23 3.3 owod fig $3 2:6 $2 3.“ 2 3 owd vmé 8.3 ooo.o fig 3A ommd 3&6 5N 2 E vod ood E»: oood 22. vmA oomd N2... mom 2 2 Hwd x2. vod ovo.o $3. ood oom.o mvHd omm 2 m.“ gem mod S... oo.v vood mwod wwd 2:... 2.2. .. 1E w.“ Z 3... S... 2E vmod owod ood Efid $2. mo; 2 2 2a vmd 3m vmod moo.o owd ovg $2. mom mm o mvd mvd 2E oood N2... vod $2. $2. om.m T w v <3. mod owv. ooo.o is... £3 m2... 2.2. mm.m S 3 mod 3d 3d 52. moo.o mo; 2N... £2. fixm 2 2 omd :3 3d v22. omod EA $2. $3. mmm vfi o 2.50 mod omd omd $3. sad 2E Hvmd $2. oo.m u: m and omd omd 22. mvo.o N3 $2. $2. 5a w.“ v \ w 3E3 o. .2 23 mvd 3v mood ovod mwd 3:... 2.3. mo.m am .3 wmd odd mod oood mvod :2 $2. 3.2. 34 mm 3 2e mod 3d ovod wood vod 33 32. 8a om o 28m S... mud omd voo.o is... 22 S3. $2. mom om w vmd omd mod fiofid owod 3A m2... 33 v3 3 v m o mnonofi v unacoi m mficofi v mspcofi m @2235 v msunofi m 3 .30 3. dug 3. .30 ow doO om. .52 3. duO om .30 om: 5x3 .5230 a». n32 uom. .30 uom. .30 -3. fiwi vom. .30 -3. .30 -3. dag -2... .30 om. .30 paw? |I|| 53% .30? uomdo divans awQ omano>< JQGOS non omwaw>< "$.55 3a owauw>< mo 3am» Hum modum @253 .238? W205 .232; mnsam “BEE .222 wiméflw oz 0M4 E30 #5 wmauwiw £5.90 own m: nu?» 3 Nfiwuauoa 12:55 moo: 3w»: vim 3E3 33 E qouwflau .2- muemuun __ao-8-u_:.:-m win .u.:.:€-.z-__& oZfi-oomflcu E v15: “EH05 dis Jsmmo: M53?“ .23»: Mini-now E Baum .3 5B9? ma suBouU 4m 05am. VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN s9 ACKNOWLEDGMENTS Grateful acknowledgment is made to fellow staff members and to the many others who have had a share in this study. To the personnel of the three San Antonio schools for their splendid and faithful cooperation-city school superintendents Mr. Marshall John- ston and Mr. E. H. Hartley; supervisors of the elementary schools, Misses Elma Neal and Alice Breeding; principals of the schools, Mr. Ray Kay and Miss Elsie Jordt of Beacon Hill School, Miss Sarah S. King of Bowie School, and Mr. S. H. Gates of Grant School; and to the teachers and pupils in each school. To Mr. J. H. Jarboe who kindly provided copies of the meteorological summaries from the U. S. Weather Bureau in San Antonio for the months and years in which data were collected. To the late Mr. Fred Small, city sealer of weights and measures in San Antonio for testing the scales. To Mr. T. R. Hamilton, associate professor of accounting and statistics, for advice regarding statistical treatment of the data. SUMMARY AND CONCLUSIONS Data in this project were collected with the cooperation of three public schools in San Antonio, each providing a representative population of approximately 500 pupils in one race-white, Mexican, or negro. Of this number, 324 white children, 277 Mexican, and 298 negro had complete weighing records for one or two years; 176 white, 118 Mexican, and 288 negro children, complete height records for one year; and 72 white, 35 Mexican, and 158 negro children, complete height records for two years. Only these complete records were used in analyzing the data for seasonal variation and distinctive racial differences in growth rates. The average of yearly net gains in weight was 7% pounds for the children of the white race and 81/2 pounds for both the Mexican and negro children whose groups included slightly larger proportions of older indi- viduals than did the white. Evidence of seasonal variation of growth in weight was sought on the bases (1) of average net gains per child derived from group weights, (2) comparison of the contribution made by gainers and losers to the net monthly gain, (3) examination of the individual records of 98 pupils (42 white, 28 each of Mexican and negro) who showed no loss between any two consecutive weighings. The spring season included February, March, and April; the summer period extended from May through Sep- tember; and fall included October, November, December, and January. The results in all analyses show that race likenesses are much more pronounced and consistent than race differences. For all three races, fall was slightly the best season for gaining. The monthly gain inithe four fall months averaged about 10 per cent of the entire yearly gain. Slight racial difference in seasonal variation was found in the relative 70 BULLETIN NO. 510, TEXAS AGRICULTURAL EXPERIMENT STATION spring and summer rates of gain. The negro group had almost as high an average monthly percentage of the yearly gain in summer as in fall and a distinctly lower rate of growth in spring, while the white children had less difference than the negroes; the Mexicans’ average monthly gain ‘in summer more nearly resembled their fall gains in one year, but their spring gains in the other year. Among the three races, October was conspicuous for consistently excellent gains (from 11.3 per cent to 16.1 per cent of the yearly gain), and April, for uniformly poor gains (from 1.4 per cent to 6.4 per cent of the yearly gain). October gains for white children were about l/é as much as the gain in the preceding five summer months, for the Mexicans, 1/ 3 as much, and for two of the four negro groups, 1% as much. ' The variation between the three races, and within the Mexican race, in relative proportion of the yearly gain made in spring and in summer, suggests that some other factor (or factors) was exerting an effect upon rate of gaining weight, along with any biological phenomenon which tends to express itself in rhythmic seasonal variation. The small and irregular race differences can scarcely be attributed to inherent racial character- istics without elimination of all other factors that may influence growth, and such elimination cannot be made from the data of this study. The records of individual monthly weight changes show that all three races have higher ratios of gainers to losers in fall months than in those of spring. In all three races, most average monthly gains made by the gaining group were near 1 to 1.25 pounds. The average amount of monthly loss was from 0.55 to 0.78 pound for all three races. Whatever factor (or factors) was more favorable to growth in fall than in spring months influenced the proportion of children who gained in weight, rather than the average amount of weight gained or lost. The chief racial difference found with individual monthly weight changes was in the ratio of gainers to losers, an average of approximately three times as many white and Mexican children gaining each month as losing, while only twice as many negroes gained as lost. Approximately 2/3 of the individual records of the constant gainers agreed with the trends shown by the monthly weight changes and by the average net gains derived from group weights. However, it is evident that in many individual cases neither spring nor summer is incompatible with excellent growth, since 37 of 98‘ children had a higher rate of gain either in spring or summer than in fall. The records of individual children -considered separately i indicate that any natural impulse to rhythmic seasonal variation does not express itself uniformly for all individuals of any of the three races living in the same city and observed at the same time, or else this inherent tendency is overbalanced at one season or another by one or more other factors which influence the rate of growth. Each child should be regarded individually in his course of growth. A child’s failure to gain should not be attributed complacently to the season of the year. Too much departure from regularity of gain VARIATIONS OF GROWTH IN WEIGHT AND HEIGHT OF CHILDREN 71 calls for special attention, although the degree of uniformity to be ex- pected in normal growth must be determined by further study. Seasonal variation of growth in weight appeared not to be influenced by sex, age, birth-month, type of body-build, or living conditions as indi- cated by the average number of rooms per person in the house and the presence or absence of a bathroom. - No explanation of the excellent gains made in October or the poor gains in April was afforded by examination of the records of weight changes in relation to the records (1) of food eaten for from two to four days within the weighing period, (2) of minor illnesses, especially colds, or (3) of climatic conditions as indicated by U. S. Weather Bureau records. Average monthly gains in height, both standing and sitting, for both the entire group of each race and age groups of white and negro children show exceedingly small and negligible differences in spring-to-fall and fall-to-spring periods. Weight gains over the same periods, in contrast to height gains, show consistently a seasonal difference, being greater in the fall-to-spring than in spring-to-fall period. It appears from the data of this study that growth in height was relatively uniform through the year, or perhaps marked difference in rate was confined to shorter time intervals than those used in this study. LITERATURE CITED 1. Baldwin, Bird T. 1927. Anthropometric measurements of children and adults. The Iowa Child Welfare Research Station, Iowa City, Iowa (unpublished). 2. Baldwin, Bird T. and Wood, Thomas D. 1931. Weight-height-age tables in English units of American-born boys and girls (clothed) of school age. The Iowa Child Welfare Research Station, Iowa City, Iowa. 3. Bowditch, H. P. 1877. The growth of children. Eighth Annual Report of the Massachusetts State Board of Health, p. 273. 4. Bowditch, H. P. 1879. The growth of children. Tenth Annual Report of the Massachusetts State Board of Health, p. 33. 5. Chaney, M. S. 1923. A comparison of the value of milk and oranges as supplementary lunch for underweight children. Am. J . Dis. Child., 26:337. 6. Chaney, M. S. and Cross, E. N. 1928. Seasonal variation in the growth of children.—A study of 567 children in the open air schools of Kansas City, Missouri. Abstract, J. Home Econ., 20:757. 7. Emerson, Haven. 1927. Seasonal variation in growth of school chil- dren. J. A. M. A., 89:1326. 8. Field, James A. 1917. Some advantages of the logarithmic scale in statistical diagrams. J. Pol. Eco., 25:805. 9. Gebhart, John C. 1924. The growth and development of Italian chil- dren in New York City. New York Assn. for the Improvement of the Condition of the Poor. New York City. l0. Hitchings, F. W. and Fitz, G. W. 1902. Seasonal variations in growth of boys. Gaillard’s Med. J., 77:216. 11. Hunt, Jean Lee, Johnson, Bufford J., and Lincoln, Edith M. 1921. Health education and the nutrition class. E. P. Dutton and Co. 12. Lucas, William Palmer and Pryor, Helen Brenton.- 1931. Physical gnfasliégements and physiologic processes in young children. J . A. M. A., 72 13. 14. 15. 16. 17. 1s. 19. 20. 21. 22. 23. 24. 25. 26. 27. . Thompson, Helen B. and Scholtz, Anna. BULLETIN NO, 510, TEXAS AGRICULTURAL EXPERIMENT STATION Ueber Periodizitat im Gewicht der Kinder Malling-Hansen, P. R. 1883. Reviewed by Roberts. Nu- an taglichen Wagungen, Kopenhagen. trition work with children, p. 82. Mitchell, Harold H. 1932. A study of factors associated with the growth and nutrition of Porto Rican children. Human Biology, 4:467. Nylin, Gustav. 1929. Periodical variations in growth, standard meta- bolism, and oxygen capacity of the blood in children. Acta Medica Scandinavica Supplementum 31. Orr, J. B. and Clark, M. L. 1930. school children. Lancet, 2:365. Palmer, Carroll E. 1933. Seasonal variations of average growth in weight of elementary school children. U. S. Pub. Health Rpt., 48: (No. 9) 211. Porter, W. T. 1920. The seasonal variation in the growth of Boston school children. Am. J. Physiol., 52:121. Porter, W. T. 1922. The relative growth of individual Boston school boys. Am. J. Physiol., 61:311. Roberts, Lydia J. 1927. Nutrition Work with children. The Uni- versity of Chicago Press. Scammon, Richard. 1931. Report, Committee A—Growth and develop- ment. White House Conference on Child Health and Protection. Sup- plement to the United States Daily, Section II, 6: (No. 29) 5. Sumner, Emma E. and Whitacre, Jessie. 1931. Some factors affecting accuracy in the collection of data on the growth in weight of school children. J. Nutrition, 4:15. Seasonal variation in growth of 1934. A study of the dietary and growth rates of 24 girls, 6 to 15 years of age, while recovering from varying degrees of malnutrition. J. Am. Diet. Assn., 9:462. Turner, C. E. 1933. Seasonal fluctuation in growth with special ref- erence to the clothing factor. Res. Quart. Am. Phys. Ed. Assn., 4:177. Veeder, B. S. and Rohlfing, E. H. 1927. Studies in pubescent growth, with special reference to periodic gain. Am. J. Dis. Child., 34:211. Whitacre, Jessie. 1934. The diet of Texas school children. Tex. Agr. ‘Exp. Sta., Bul. 489. Wilson, Edwin B. 1931. Report, Committee A—Growth and develop- ment. White House Conference on Child Health and Protection. Supplement to The United States Daily, Section II, 6: (No. 29) 3.