PART II.. Mass Studies in Heredity of Adult Build.

MASS STUDIES IN HEREDITY OF ADULT BUILD.

It is a matter of common observation that in some families the parents and children are all slender; in others, there may be many examples of obesity. Worthington (1877, p. 50) cites a number of examples from C. Bouchard. A woman of 45 years weighs 107 kg. (236 pounds); her obesity began shortly after marriage; her father is very obese and her mother obese. A woman of 49 years, whose father is a Turk and whose mother is French, weighs 117 kg. or about 258 pounds; her mother was obese. A woman of 115 kg. or about 250 pounds has an obese mother and two sisters who were obese in infancy; also a gouty mother’s father and father’s father.

The following, from Chambers (1850), show obesity “on both sides of the house”: Male of 28 years, 120 kg. (266 pounds); woman of 48 years, 127 kg. (280 pounds); woman of 52 years, 98.4 kg. (217 pounds); man of 57 years, 227 kg. (500 pounds); woman of 58 years, 104 kg. (231 pounds); woman of 68 years, 118 kg. (260 pounds); woman of 70 years, 107 kg. (238 pounds). In many other cases cited by Chambers, one parent of the obese patient was obese. Howard (1908, p. 54) cites the case of a 7-year-old girl, 45.5 inches (115.6 cm.) tall, who weighed 40 kg. (88 pounds), had a pendulous abdomen, and was feeble-minded. Her sibs were not abnormal and her parents were of average build. One of her great uncles weighs 127 kg. (280 pounds), an uncle, at 40 years, about 109 kg., and an aunt of 31 years, 95 kg. (210 pounds). This case is instructive because of the skipping of a generation.

In the class of obese cases known as adiposis dolorosa, heredity is usually obvious. Price (1909) cites a case of an obese woman of 48 years and weighing 140 kg. (310 pounds) who belongs to a fraternity of 7; 1 was a miscarriage, 2 died young of accident, 1 died at 22 of typho-pneumonia, 1 died young of scarlet fever, and 1 brother is large and rheumatic. The father seems to have been of average build and the mother is stated to have been “very thin.” Of her sibs, 6 were fleshy or very fleshy, 1 medium, and 1 slender; the children of these fleshy sibs of the mother are “all stout.”

Lyon (1910, p. 68) discusses heredity in adiposis dolorosa and lipomatosis and cites a considerable number of cases of family recurrence in his cases and others. Thus he twice treated a father and his son for multiple fatty tumors; also twice a mother and daughter. Lyon’s obese case No. 5 was like her 3 sisters and 1 daughter; a son of her father’s brother showed similar fatty deposits. 10 other instances of family recurrence of abnormal fat deposit are cited.

Maranon and Bonilla (1920) cite the case of a girl of 18 years who was slender, like her parents, until after an attack of syphilis, when she came to weigh 157 kg. or 350 pounds, while her height was 160 cm., her chest-girth 130 cm., and that of her abdomen 150 cm. or 90 per cent of her height. She had a very large brother, and both mother’s parents were obese, though the parents were not known to be so.

Such examples might be multiplied indefinitely.

Our problem is not what are all the causes of this diversity of build, but rather in how far do genetical factors play a part in this diversity. We are not oblivious to the fact that there are many factors responsible for the result—deviation from the average build. These we shall consider in detail in a later section, and the consideration will help us to see the limits to the action of the genetical factors. Before going on to that, we shall have to consider more in detail the nature of the facts for which an explanation has to be sought.

METHODS AND MATERIALS.

The method of analyzing the genetic factors in build is that of tabulating the distribution of aberrant builds in the family network. There is required, first, a large mass of family data which includes many extreme or aberrant types of build, and which is as reliable and as accurately quantitative as possible; secondly, this has to be subjected to the ordinary methods of genetic analysis.

The available material has consisted of data on stature and weight given in the Records of Family Traits which constitute a fair sample of the population; and of quantitative data on special schedules giving stature and weight of a fraternity, its parents, uncles and aunts, and grandparents. These special schedules had been mailed to an address list of overweight and underweight persons obtained through the kind cooperation of Mr. Arthur Hunter. Those who returned the schedules showed an especial appreciation of the requirements of our study. A third source was the A file of the Eugenics Record Office, where are gathered miscellaneous pedigrees of families showing aberrancy in build. A fourth and especially valuable source was the field work of Miss Louise A. Nelson, of the Eugenics Record Office; this started with selected, usually obese, cases.

After the data had been assembled and tabulated, a certain amount of correspondence and personal visitation was undertaken in order to secure a confirmation or revision of the records in hand. In some cases this brought to light errors in the records, in others, useful details. Naturally, it was not possible to secure a revision of all of the data used, but an attempt was made to select only records that had been compiled with care and conscientiousness, and these traits in the compiler reveal themselves pretty clearly to a person who has examined thousands of these records, just as carelessness is revealed also by slipshod speech or posture.

For our study we desire the data of stature and weight for children, parents, and grandparents. With some exceptions only those families are studied in which all these data are accurately given. Also, only children who are above 18 years of age can be utilized, because stature changes so rapidly until that age. However, since it is build and not stature we are studying, the fact of increase of stature from 19 to 21 years of age affects the result very little. Finally, in a certain proportion of the cases the stature and weight of all of the grandparents are not given quantitatively. Such families are utilized, nevertheless, with such quantitative data as may have been afforded.

The data were taken from the Records of Family Traits by Miss Miriam Kortright, who long assisted in our statistical work. The computations of index of build were made by Miss Kortright and Mr. William Kraus, Miss Laura Craytor, and Miss Margaret Andrus, who checked one another’s work. The tabulation and seriations of the indices were done by Misses Margaret Babcock and Katharine Belzer.

THE ADULT INDEX OF BUILD.

In an earlier section of this paper the question of the best index of build has been discussed generally. It was pointed out that many regard it as a truism that build is a relation of volume to stature. Since the volume of a person’s body is rarely known, and it is difficult to determine it, weight has been substituted for volume. However, this substitution assumes that specific gravity is the same for slender and for fat persons; but this is not at all the case. The specific gravity of a fat person is about that of water (0.978 to 1.079 in 4 children 7 to 13 years of age, Meeh, 1879, and 1.014 in a 61-year-old man of 98 kg. weight, Mies, 1899); of a thin person it may be 5 to 8 per cent above that of water (1.049 to 1.082 for thin convicts, Mies, 1899). This variable specific gravity complicates the attempt to infer volume from weight. In view of these difficulties it were better to measure build by a relation of chest diameter (or circumference) to stature. But this ratio can not be used in our studies, since our data, for the most part, give only weight and stature and not chest-girth. It remains thus to determine the closest relation between weight and chest-girth. This determination I have attempted to make for 100 young men, 20 to 25 years of age, measured at Harvard University where they were students. It will hardly be worth while to reproduce the detailed tables of measurements and ratios, but they will be found summarized in table 8. In this table is given the frequency of occurrence of each of the different ratios (or rather classes of ratios) found using chest-girth in first, second, and third powers as a divisor. If weight varied exactly with the chest-girth, then the ratio of the former to the latter should remain constant. Such a strict relation is hardly to be expected and, of course, is not found. The ratios obtained show a certain variability about the mean condition, and this variability is measured by the standard deviation. Similarly, if each weight be divided in turn by the second and third powers of stature, and the corresponding variability of the ratios be considered, we shall have a method of deciding whether weight varies more closely with the first, second, or third power of chest-girth, and which of those powers gives in its fluctuations the best measure of the corresponding fluctuations in weight.

TABLE 8.—Variability of weight in relation to the second and third powers of chest-girth as found in 100 Harvard students.

+------------------+-------------------+-------------------+ | Weight ÷ | Weight ÷ | Weight ÷ | | chest-girth | chest-girth² | chest-girth³ | +------------------+-------------------+-------------------+ | f | f | f | | 610 to 619 1 | 690 to 700 1 | 711 to 720 1 | | 640 649 3 | 711 720 1 | 761 770 3 | | 660 669 2 | 731 740 1 | 791 800 3 | | 670 679 4 | 741 750 1 | 801 810 3 | | 680 689 6 | 751 760 5 | 811 820 3 | | 690 699 2 | 761 770 2 | 821 830 3 | | 700 709 7 | 771 780 4 | 831 840 3 | | 710 719 6 | 781 790 11 | 841 850 5 | | 720 729 4 | 791 800 10 | 851 860 1 | | 730 739 10 | 801 810 7 | 861 870 10 | | 740 749 7 | 811 820 9 | 871 880 6 | | 750 759 7 | 821 830 8 | 881 890 3 | | 760 769 6 | 831 840 5 | 891 900 5 | | 770 779 4 | 841 850 3 | 901 910 5 | | 780 789 7 | 851 860 4 | 911 920 3 | | 790 799 5 | 861 870 9 | 921 930 2 | | 800 809 2 | 871 880 3 | 931 940 7 | | 810 819 3 | 881 890 4 | 941 950 1 | | 820 829 3 | 891 900 3 | 951 960 4 | | 830 839 3 | 901 910 4 | 961 970 4 | | 840 849 4 | 921 930 2 | 971 980 9 | | 850 859 1 | 951 960 1 | 981 990 1 | | 870 879 1 | 961 970 2 | 991 1000 5 | | 900 909 1 | | 1001 1010 2 | | 920 929 1 | | 1031 1040 1 | | | | 1041 1050 4 | | | | 1061 1070 2 | | | | 1111 1120 1 | | | | | | σ, 58.32 | σ, 51.50 | σ, 76.99 | +------------------+-------------------+-------------------+

A comparison of the standard deviations gives the following results for man:

weight weight weight Ratio: ----------- ------------ ------------ chest-girth chest-girth² chest-girth³ Standard deviation: 58.3 51.5 77.0

From these results the conclusion is drawn that since the variability (standard deviation) of weight ÷ chest-girth² is least, the square of the chest-girth varies more closely with weight than either the first or third power of chest-girth; consequently the square of chest-girth is the best measure of weight of the three.

By hypothesis, the chest-girth in persons of the same build varies very closely or exactly with stature; consequently we could substitute in the foregoing ratios for chest its average equivalent, stature/K, in which K is nearly 2, more precisely 1.9. In any case it is thus clearly deducible that a better index of build is got by dividing weight by the square of stature than by its cube, as has been so often done. Accordingly, the ratio of weight to stature² has been adopted in this paper as the standard index of build. The correlation between this index of build and relative chest-girth is found by calculation to be about 0.45.

In any scale of index of build it is, of course, desirable to use the metric system. Unfortunately, most of our data are in English units, so that our indices were first obtained by the use of these units. We have in many cases transmuted the English into the equivalent metric measures. We have, however, retained the original English index, since a large portion of the more cultured part of the world uses that system in daily life. A table to facilitate transmutation is also given in the Appendix, table XVIII. To facilitate the determination of the index of build when stature and weight (in English or metric units) are known, table XVI has been prepared (pages 169, 170).

To avoid decimals, the ratio, weight in pounds ÷ (stature in inches)² is multiplied in this book by 1,000; this gives a series of ratios running from 20 to 60 and over. To avoid confusion with the English system, the metric equivalents are taken as the ratio of weight in grams ÷ (stature in centimeters)². This gives a series of index numbers of the order 1.5 to 4.0; in this case, at least, one decimal is always expressed. The small integral figure and the decimal at once indicate that the index is from metric units. Since the index of build has often been expressed as the ratio of weight to, respectively, stature, stature²⸳⁵, and stature³, table XVII has been prepared to permit these ratios to be transmuted into weight ÷ stature², English system.

CLASSIFICATION OF BUILD.

For the purposes of analysis, it was found necessary to make a small number of classes of build. To decide upon the limits of these classes, a polygon of frequency of all indices of build was made, as shown in figure 7. It appeared plain at the outset that it is desirable to plot the data in this polygon by using as abscissæ the logarithms of the index of build rather than the absolute indices, since the range of weight above the mode is, for obvious reasons, very much greater than below the mode. Taking mean weight at 68 kg., or 150 pounds, the minimum weight is about 20 kg. (45 pounds), or 25 kg. (55 pounds) below the mean, and the maximum weight is about 150 kg. (330 pounds), or 182 kg. (400 pounds) above the mean. That is, the range of weight classes is three times as great above as below the mean. Plotting data in logarithmic fashion, as shown in figure 7, it appears that the modal index of build is 2.3 (33). The range is from 1.4 (20) to 4.5 (64). Using the logarithms of abscissæ, the curve is more nearly a symmetrical one. It is more irregular above than below the mode, because the classes are more numerous and the frequency of each class smaller. The presence of two modes is suggestive of the hypothesis that the medium class and probably the fleshy classes are not strictly homogeneous, but, on the contrary, comprise groups of individuals whose build is due to dissimilar factors, or sets of factors.

To derive the desired classes from figure 7, the polygon was somewhat arbitrarily divided into five parts, as indicated. Taking 33.5 as a starting-point, an equal logarithmic distance was laid off, above and below this point, on the base-line. This was taken as the range of middle class. An equal logarithmic range was accorded the classes next above and below the median respectively. All of the remainders were thrown into the extreme classes to which are given, thus, a somewhat greater range than the interior classes. This seemed desirable, since their frequencies were so low. The adjusted classes finally adopted are as shown in table 9.

TABLE 9.—The five standard classes of build; limits and middle points of each.

+----------------------+-------------------------------------------+ | | Range of indices. | | +---------------+--------------+------------+ | Class. | | | Middle | | | Metric. | English. | of class | | | | | (English). | +----------------------+---------------+--------------+------------+ | Very slender (V. S.) | 1.40 to 1.80 | 20 to 25.4 | 23.5 | | Slender (S.) | 1.81 2.14 | 25.5 30.4 | 28.0 | | Medium (M.) | 2.15 2.56 | 30.5 36.4 | 33.5 | | Fleshy (F.) | 2.57 3.05 | 36.5 43.4 | 40.0 | | Very fleshy (V. F.) | 3.06 4.50+ | 43.5 64 + | 48.0 | +----------------------+---------------+--------------+------------+

SIGNIFICANCE OF VARIATIONS IN BUILD.

What is the meaning of the great variations of build described in the preceding paragraph? What is known in this matter may here be briefly summarized that it may be held in mind in considering the numerous cases to which we shall have occasion to refer.

In general, it may be stated that variations in build are due to endogenous causes and exogenous causes. In this book we shall have occasion to examine especially the former—the constitutional or hereditary factors. These include idiosyncrasies of metabolism, in part controlled by peculiarities in the functioning of the endocrine glands; in part, probably, by even finer protoplasmic differences. Thus it is known that the thyroid gland greatly influences metabolism; its activity in growing children tends to produce tall and slender form. On the other hand, deficiency in its activity in childhood leads to the type of obesity known as cretinism, and in middle life to myxedema. The secretions of the pituitary gland cooperate with the thyroid in stimulating growth, especially in the preadolescent stage. When pituitary secretions are deficient there frequently results, it is believed, the adiposogenital syndrome, in which great masses of fat are deposited on breasts, abdomen, hips, and buttocks, and the gonads remain infantile. A case that quite certainly belongs to this category is shown by Beck (1922, p. 881) and reproduced in plate 8, figures 3, 4, 5; 3 of this man’s 4 sibs are fleshy and have scant beards. This is quite like our standard very fleshy case (plate 2, fig. 5). See, also, the extreme cases falling under this category described by Lyon, 1910.

Lesions of the pineal gland (Beck, 1922, p. 909) and of the gonads are stated in some cases to induce obesity. Certain it is that, on the other hand, the activity of the gonads tends to slow up growth in stature and to increase the chest circumference (plate 6), and this change is more marked in the male than the female.

The exogenous causes of build are striking, so much so that many physiologists seem to accept the hypothesis that they are of sole importance, that excess of fat is due merely to excess of calories ingested over those concerned in bodily activity. While no one will deny the possibility of starving most fleshy persons thin or of increasing the weight of most adults by an excess of food, yet it is also obvious that two persons of the same stature and fed equal amounts of similar food may come to differ enormously, due to internal conditions, sometimes of glandular origin and sometimes dependent upon, or at least associated with, disease.

TABLE 10.—Incidence of disease in relation to build.

+-------------------+-----------------+-------------------+-----------+ | | In 10,000 of | | | | | standard | In persons of | | | | population. | selected build. | | | +------+----------+------+------------+-----------+ | Diagnosis of | 1. | 2. | 3. | 4. | 5. | | disease. | | | | Per cent | | | | No. | Per cent | No. | afflicted | Ratio of | | | of |afflicted.| of |in 69 V. S. | col. 4 to | | |cases.| |cases.|population. | col. 2. | +-------------------+------+----------+------+------------+-----------+ |VERY SLENDER BUILD.| | | | | | | | | | | | | | YOUTH. | | | | | | |Influenza | 7 | 0.07 | 2 | 2.81 | 40.14 | |Tuberculosis | 24 | .24 | 2 | 2.81 | 11.70 | |Colds | 48 | .48 | 3 | 4.34 | 9.04 | | | | | | | | | MIDDLE AGE. | | | | | | |Melancholia | 10 | .10 | 2 | 2.81 | 28.10 | |Nervousness | 130 | 1.30 | 6 | 8.60 | 6.62 | |Tuberculosis | 58 | .58 | 2 | 2.81 | 4.85 | +-------------------+------+----------+------+------------+-----------+ | | | | | Per cent | | | SLENDER BUILD. | | | | afflicted | | | | | | | in 737 S. | | | YOUTH. | | | |population. | | |Fevers | 4 | 0.04 | 4 | 0.542 | 13.55 | |Adenoids | 10 | .10 | 9 | 1.22 | 12.20 | |Appendicitis | 28 | .28 | 13 | 1.76 | 6.28 | |Anemia | 11 | .11 | 5 | .68 | 6.16 | |Tuberculosis | 24 | .24 | 10 | 1.35 | 5.62 | |Tonsilitis | 104 | 1.04 | 30 | 4.07 | 3.91 | |Bronchitis | 53 | .53 | 12 | 1.62 | 3.06 | |Pneumonia | 165 | 1.65 | 34 | 4.61 | 2.79 | |Nervous breakdown | 74 | .74 | 15 | 2.03 | 2.74 | |Rheumatism | 117 | 1.17 | 16 | 2.17 | 1.85 | |Diphtheria | 150 | 1.50 | 19 | 2.57 | 1.71 | |Scarlet Fever | 281 | 2.81 | 29 | 3.93 | 1.40 | |Typhoid fever | 253 | 2.53 | 25 | 3.39 | 1.34 | | | | | | | | | MIDDLE AGE. | | | | | | |Anemia | 3 | .03 | 3 | .407 | 13.57 | |Intestinal trouble | 4 | .04 | 3 | .407 | 10.17 | |Appendicitis | 23 | .23 | 9 | 1.220 | 5.30 | |Tuberculosis | 58 | .58 | 22 | 2.980 | 5.14 | |Heart disease | 94 | .94 | 15 | 2.030 | 2.16 | |Pneumonia | 139 | 1.39 | 22 | 2.980 | 2.14 | |Typhoid fever | 138 | 1.38 | 16 | 2.170 | 1.57 | +-------------------+------+----------+------+------------+-----------+ | | | | | Per cent | | | FLESHY BUILD | | | | afflicted | | | | | | | in 543 F. | | | YOUTH. | | | |population. | | |Adenoids | 10 | 0.10 | 3 | 0.553 | 55.30 | |Scarlet fever | 281 | 2.81 | 36 | 6.642 | 2.36 | |Typhoid fever | 253 | 2.53 | 28 | 5.166 | 2.04 | |Pneumonia | 165 | 1.65 | 17 | 3.136 | 1.90 | | | | | | | | | MIDDLE AGE. | | | | | | |Hernia | 8 | 0.08 | 7 | 1.29 | 16.00 | |Arterio-sclerosis | 9 | .09 | 6 | 1.10 | 12.22 | |Bladder trouble | 10 | .10 | 6 | 1.10 | 11.00 | |Measles | 10 | .10 | 6 | 1.10 | 11.00 | |Appendicitis | 23 | .23 | 12 | 2.22 | 9.65 | |Eczema | 6 | .06 | 3 | 0.55 | 9.17 | |Hemorrhoids | 13 | .13 | 5 | 0.92 | 7.11 | |Liver trouble | 16 | .16 | 6 | 1.10 | 6.88 | |Paralysis | 49 | .49 | 18 | 3.38 | 6.80 | |Heart trouble | 94 | .94 | 34 | 6.28 | 6.69 | |Gallstones | 22 | .22 | 8 | 1.47 | 6.68 | |Apoplexy | 27 | .27 | 8 | 1.47 | 5.44 | |Tumor | 18 | .18 | 5 | 0.92 | 5.13 | |Bronchitis | 38 | .38 | 9 | 1.66 | 4.37 | |Erysipelas | 31 | .31 | 7 | 1.29 | 4.16 | |Cancer | 51 | .51 | 10 | 1.84 | 3.61 | |Pneumonia | 139 | 1.39 | 27 | 4.98 | 3.58 | |Malaria | 43 | .43 | 8 | 1.47 | 3.42 | |Typhoid fever | 138 | 1.38 | 22 | 4.06 | 2.95 | |Kidney trouble | 74 | .74 | 11 | 2.03 | 2.74 | |Rheumatism | 349 | 3.49 | 37 | 6.82 | 1.95 | +-------------------+------+----------+------+------------+-----------+ | | | | | Per cent | | | VERY FLESHY BUILD.| | | | afflicted | | | | | | |in 103 V. F.| | | YOUTH. | | | |population. | | |Pneumonia | 165 | 1.65 | 7 | 6.79 | 4.115 | | | | | | | | | MIDDLE AGE. | | | | | | |Dropsy | 14 | 0.14 | 3 | 2.91 | 20.80 | |Stomach trouble | 15 | .15 | 3 | 2.91 | 19.40 | |Apoplexy | 37 | .37 | 5 | 4.85 | 11.40 | |Kidney trouble | 74 | .74 | 8 | 7.76 | 10.60 | |Cancer | 51 | .51 | 4 | 3.88 | 7.61 | |Heart disease | 94 | .94 | 6 | 5.82 | 6.20 | |Pneumonia | 139 | 1.39 | 8 | 7.76 | 5.6 | |Malaria | 43 | .43 | 2 | 1.94 | 4.5 | |Typhoid fever | 138 | 1.38 | 6 | 5.82 | 4.2 | |Rheumatism | 349 | 3.49 | 10 | 9.70 | 2.8 | +-------------------+------+----------+------+------------+-----------+

Very slender build: A. Youth; expectation for cases of measles, 2; found, none.

Slender build: A. Youth; expectation for cases of whooping-cough, 7; chicken-pox, 4; colds, 4; croup, 3. Cases found, none. B. Middle Age; expectation for cases of eye trouble, 30, erysipelas, 24, tonsillitis, 23, and apoplexy, 21. Cases found, none.

Fleshy build: A. Youth; expectation for cases of ear trouble, 19, lung trouble, 18. Cases found, none. B. Middle age; expectation for cases of throat trouble, 5. Cases found, none.

DISEASES IN RELATION TO BUILD.

As just stated, it is frequently true that build is influenced permanently by disease. To test the influence of disease on, or association of diseases with, different types of build, a tabulation was made of the diseases recorded (in the Records of Family Traits, Eugenics Record Office) as occurring during youth and during middle age in 10,000 fairly well described persons. This constituted the control. Then there was determined for our groups of very slender, slender, fleshy, and very fleshy, the incidence of disease. The ratio of the percentage incidence of the latter to the former was then calculated. In table 10 is given in sum many of the results found for the principal diseases. This table may now be briefly discussed.

Persons of very slender build are characterized in youth by an excess of respiratory diseases—influenza, tuberculosis, and colds. In middle age they show an excess of melancholia, nervousness, and tuberculosis.

In 737 persons of slender build there are found in youth many diseases in excess of normal incidence. These comprise diseases of the respiratory tract—tuberculosis, tonsillitis, bronchitis, pneumonia; some nervous diseases, “nervous breakdown”; various general infections, such as “fevers,” appendicitis, anemia, “rheumatism,” diphtheria, scarlet and typhoid fevers. One might conclude that slender youth are relatively nonresistant to infections. In slender persons there is found in middle age an excess of tuberculosis and pneumonia, much appendicitis and intestinal trouble, and (as also in youth) anemia.

These associations of slender build and disease are not always easy to interpret. The common idea of the tubercular diathesis comprises slender form. On the other hand, a person who has, or has recovered from, active pulmonary tuberculosis is apt to remain underweight, partly because the respiratory apparatus is damaged. The association of “nervousness” with slenderness is probably due to the double effect of some glandular dystrophy, as, for example, of the thyroid gland. Hyperthyroid individuals are usually tall, slender, and “nervous” or irritable.

In 103 persons of very fleshy build, the only outstanding disease of youth is pneumonia. In middle age occur “kidney trouble,” “dropsy” (which often accompanies chronic nephritis), and apoplexy, which is sometimes caused by extra pressure on the blood-vessels resulting from impeded elimination from the kidney or to a diabetic tendency which puts extra work on the vessels. “Heart disease” is also commoner than usual.

In 542 persons of fleshy build, “bladder trouble” (probably including diabetes) and kidney trouble are exceptionally frequent, also arterio-sclerosis and its accompaniments, apoplexy and paralysis. Hernia is frequent, as are various diseases of the digestive tract, such as appendicitis, hemorrhoids, liver trouble, and gallstones. These are doubtless not the cause of, but a consequence or concomitant of, overweight. Sibilant bronchitis, lithiasis (uric and biliare), and diabetes mellitus are mentioned, in addition to the above, by Heckel (1920, p. 31) as especially apt to be associated with obesity.

TABLE 11.—Distribution of progeny of the different matings according to index of build; males and females tabulated separately.

+----------------------------------------------------------------+ | Distribution of male progeny. | +----------------------------------------------------------------+ |Index of build (English) | | +---+---+---+---+---+----+---+---+---+----+----+---+---+-----+ | |VS |VS | V | S | S | S | S | M | M | M | F | F |VF |Total| | |× | × | × | × | × | × | × | × | × | × | × | × | × | ♂ | | |S | M | F | S | M | F |VF | M | F | VF | F |VF |VF | | | |II |III|IV | VI|VII|VIII|IX | X | XI| XII|XIII|XIV|XV | | | +---+---+---+---+---+----+---+---+---+----+----+---+---+-----+ | 22| | | | | | | | | | | | | | | | 23| | | | | | | | | | | | | | | | 24| | | | | | | | | | | | | | | | 25| 1| | | 1| | 1| | | | 1 | | | | 4| | 26| 1| | | | 1| | | | | | | | | 2| | 27| 1| | 1| 7| | | | 1| | 1 | | | | 11| | 28| | 1| | 5| | 1| 1| 1| | | | | | 9| | 29| | 1| | 4| 3| 2| | 3| 2| 1 | 2| | | 18| | 30| | | | 5| 8| 2| 2| 13| 7| 1 | 1| | | 39| | 31| 1| | | 2| 17| 5| 1| 10| 6| 2 | 2| 1| 1| 48| | 32| | 2| 2| 3| 21| 7| 2| 18| 25| 3 | 4| 4| 3| 94| | 33| | 2| 1| 2| 23| 13| 2| 23| 26| 4 | 3| 7| 1| 107| | 34| | 2| 1| | 17| 14| 1| 16| 21| 3 | 4| 3| 1| 83| | 35| | | | | 24| 8| 2| 25| 20| 8 | 8| 5| 2| 102| | 36| | 1| | | 14| 4| | 25| 20| 1 | 9| 2| 1| 77| | 37| | 1| 1| | 12| 10| 1| 8| 14| 5 | 6| 1| 1| 60| | 38| | | 1| | 9| 9| 2| 10| 16| 3 | 9| 3| | 62| | 39| 1| | | | 6| 4| 5| 8| 5| 9 | 7| 7| 1| 53| | 40| | | 1| | 4| 2| 1| 6| 6| 5 | 4| 5| 1| 35| | 41| | | 2| | 4| 1| | 4| 10| | 1| 2| | 24| | 42| | | | | 1| 2| 1| 1| 5| 1 | 4| 6| | 21| | 43| | 1| 1| | 2| 2| | 3| 2| 1 | 3| 4| | 19| | 44| | | | | 1| | 1| | 1| 1 | | 2| 1| 7| | 45| | | | | 1| 1| | | 2| 4 | 2| | 2| 12| | 46| | | | | | | 1| 1| | 2 | | 2| 1| 7| | 47| | | | | 1| | | 1| 2| | 4| | 2| 10| | 48| | | | | 1| | | | | | | 2| | 3| | 49| | | | | | | | 1| | | | | | 1| | 50| | | | | 1| | | | | 1 | | | 2| 4| | 51| | | 1| | 1| | | | | | 2| | 1| 5| | 52| | | | | | | | | | | | | | 0| | 53| | | | | | | | | 2| | 2| 1| | 5| | 54| | | | | | | | | 1| | | | | 1| | 55| | | | | | | | | | | | | | 0| | 56| | | | | | | | | | | | | | 0| | 57| | | | | | | | | | | | | | 0| | 58| | | | | | | | | 1| | | | | 1| | | | | | | | | | | | | | | | 0| | 79| | | | | | | | | | 1 | | | | 1| |103| | | | | | | | | | 1 | | | | 1| | +---+---+---+---+---+----+---+---+---+----+----+---+---+-----+ | ♂ | 5| 11| 12| 29|172| 88 | 23|178|194| 59| 77| 57| 21| 926| | ♀ | 6| 17| 13| 18|134| 67 | 11|149|146| 53| 79| 43| 9| 745| | +---+---+---+---+---+----+---+---+---+----+----+---+---+-----+ |Total | | | | | | | | | | | | | | | ♂ | | | | | | | | | | | | | | | |and| | | | | | | | | | | | | | | | ♀ | 11| 28| 25| 47|306| 155| 34|327|340| 112| 156|100| 30| 1671| +---+---+---+---+---+---+----+---+---+---+----+----+---+---+-----+

Avg. ♂, 35.81 ± 0.12. σ ♂, 5.325 ± 0.084.

TABLE 11A.—Distribution of progeny of the different matings according to index of build; males and females tabulated separately—Continued.

+----------------------------------------------------------------------+ | Distribution of female progeny. | +----------------------------------------------------------------------+ |Index of build (English) | | +---+---+---+---+---+----+---+---+---+----+----+---+---+-----+-----+ | |VS |VS | V | S | S | S | S | M | M | M | F | F |VF |Total|Total| | |× | × | × | × | × | × | × | × | × | × | × | × | × | ♀ | ♂ | | |S | M | F | S | M | F |VF | M | F | VF | F |VF |VF | | and | | |II |III|IV | VI|VII|VIII|IX | X | XI| XII|XIII|XIV|XV | | ♀ | | +---+---+---+---+---+----+---+---+---+----+----+---+---+-----+-----+ | 22| | 1| | 1| | | | | | | | | | 2| 2| | 23| 1| | | | | 1| | | | | | | | 2| 2| | 24| | | | | | | | | | | | | | 0| 0| | 25| | | 1| 3| | 1| | 2| | 1| | | | 8| 12| | 26| 2| 1| | 3| 3| 3| | | 1| | 1| | | 14| 16| | 27| | 1| 1| 4| 2| 1| | 3| | | | 1| | 13| 24| | 28| | | 1| 1| 11| 1| | 1| 4| | 2| | | 21| 30| | 29| 1| 1| 1| 2| 10| 5| 1| 7| 5| 2| 6| | | 41| 59| | 30| 1| 2| 1| 1| 10| 6| | 10| 9| 2| 3| 2| | 47| 86| | 31| | 4| | 1| 22| 8| 2| 15| 9| 4| 2| 3| 1| 71| 119| | 32| 1| 1| 1| 2| 18| 2| 2| 12| 15| 6| 2| 2| 1| 65| 159| | 33| | 4| 2| | 12| 11| 1| 14| 20| 4| 1| 2| | 71| 178| | 34| | | 1| | 9| 4| | 12| 13| 9| 8| 2| 2| 60| 143| | 35| | | 2| | 10| 2| | 9| 13| 4| 9| 3| | 52| 154| | 36| | 1| | | 7| 2| 1| 19| 20| 2| 8| 4| 1| 65| 142| | 37| | | | | 3| 3| 1| 14| 8| 4| 7| 2| | 42| 102| | 38| | | | | 2| 5| 1| 7| 7| 2| 2| 5| | 31| 93| | 39| | | | | 2| 5| | 10| 5| 2| | 1| 1| 26| 79| | 40| | | 1| | 3| 1| 1| 3| 6| | 6| 1| 1| 23| 58| | 41| | | | | 2| 1| 1| 5| 1| 2| 2| 1| | 14| 38| | 42| | 1| | | 1| 3| | 2| 2| | 7| 3| 1| 21| 42| | 43| | | | | 2| 1| | | 1| 2| 3| 1| | 10| 29| | 44| | | | | 1| 1| | | 2| | 6| 1| | 11| 18| | 45| | | | | 2| | | 1| | 2| | 3| | 8| 20| | 46| | | 1| | 1| | | | 1| 1| | 1| | 5| 12| | 47| | | | | | | | | 2| | 1| 2| 1| 6| 16| | 48| | | | | | | | | | 1| | 1| | 2| 5| | 49| | | | | 1| | | 1| 1| 1| 2| | | 6| 7| | 50| | | | | | | | | 1| 1| | | | 2| 6| | 51| | | | | | | | 1| | | | 1| | 2| 7| | 52| | | | | | | | | | 1| 1| | | 2| 2| | 53| | | | | | | | | | | | 1| | 1| 6| | 54| | | | | | | | | | | | | | | 1| | 55| | | | | | | | | | | | | | | 0| | 56| | | | | | | | 1| | | | | | 1| 1| | 57| | | | | | | | | | | | | | | 0| | 58| | | | | | | | | | | | | | | 1| | 79| | | | | | | | | | | | | | | 1| |103| | | | | | | | | | | | | | | 1| | | | | | | | | | | | | | | | | | | +---+---+---+---+---+----+---+---+---+----+----+---+---+-----+-----+ | ♀ | 6| 17| 13| 18|134| 67| 1|149|146| 53| 79| 43| 9| 745| 1671| +---+---+---+---+---+---+----+---+---+---+----+----+---+---+-----+-----+

Avg. ♀, 34.54 ± 0.17. S. D. ♀, 5.133 ± 0.089.

The one clear conclusion from this study is that no single disease and no special single collection of diseases is exclusively responsible for exceptionally slender or exceptionally fleshy build. The variations in build are due primarily rather to various idiosyncrasies of development and metabolism which have largely an hereditary basis, upon which may be superimposed modifications by various types of disease.

TABLE 12.—Distribution of progeny of the different matings, according to index of build; sexes tabulated together, based on Appendix tables, omitting starred families.

+--------------+-----+-----+-----+-----+-----+-----+-----+ | Serial | II | III | IV | VI | VII | VIII| IX | | mating No. | | | | | | | | +--------------+-----+-----+-----+-----+-----+-----+-----+ | Type of | VS | VS | VS | S | S | S | S | | mating. | × | × | × | × | × | × | × | | | S | M | F | S | M | F | VF | +--------------+-----+-----+-----+-----+-----+-----+-----+ | Av. index | 26.1| 28.4| 32.0| 29.8| 30.9| 33.8| 37.9| | of build | | | | | | | | +--------------+-----+-----+-----+-----+-----+-----+-----+ | No. of | 4 | 8 | 5 | 23 | 101 | 49 | 11 | | matings. | | | | | | | | +--------------+-----+-----+-----+-----+-----+-----+-----+ | 22 | | 1 | | 1 | | | | | 23 | 1 | | | | | 1 | | | 24 | | | | | | | | | 25 | 1 | | 1 | 4 | | 2 | | | 26 | 3 | 1 | | 3 | 4 | 3 | | | 27 | 1 | 1 | 2 | 11 | 2 | 1 | | | 28 | | 1 | 1 | 6 | 11 | 2 | 1 | | 29 | 1 | 2 | 1 | 6 | 13 | 7 | 1 | | 30 | 1 | 2 | 1 | 6 | 18 | 8 | 2 | | 31 | 1 | 4 | | 3 | 39 | 13 | 3 | | 32 | 1 | 3 | 3 | 5 | 39 | 9 | 4 | | 33 | | 6 | 3 | 2 | 35 | 24 | 3 | | 34 | | 2 | 2 | | 26 | 18 | 1 | | 35 | | | 2 | | 34 | 10 | 2 | | 36 | | 2 | | | 21 | 6 | 1 | | 37 | | 1 | 1 | | 15 | 13 | 2 | | 38 | | | 1 | | 11 | 14 | 3 | | 39 | 1 | | | | 8 | 9 | 5 | | 40 | | | 2 | | 7 | 3 | 2 | | 41 | | | 2 | | 5 | 2 | 1 | | 42 | | 1 | | | 3 | 5 | 1 | | 43 | | 1 | 1 | | 4 | 3 | | | 44 | | | | | 2 | 1 | 1 | | 45 | | | | | 3 | 1 | | | 46 | | | 1 | | 4 | | 1 | | 47 | | | | | 1 | | | | 48 | | | | | 1 | | | | 49 | | | | | 1 | | | | 50 | | | | | 1 | | | | 51 | | | 1 | | 1 | | | | 52 | | | | | | | | | 53 | | | | | | | | | 54 | | | | | | | | | 55 | | | | | | | | | 56 | | | | | | | | | 57 | | | | | | | | | 58 | | | | | | | | | 79 | | | | | | | | | 103 | | | | | | | | | Total | 11 | 28 | 25 | 47 | 306 | 155 | 34 | +--------------+-----+-----+-----+-----+-----+-----+-----+ |Adult progeny | | | | | | | | | per mating | 2.75| 3.50| 5.00| 2.04| 3.03| 3.16| 3.09| |Average |28.55|32.18|35.04|28.47|34.01|34.39|35.68| |P. E. of aver.| ±.86| ±.54| ±.83| ±.24| ±.16| ±.22| ±.51| |σ | 4.21| 4.20| 6.18| 2.41| 4.20| 4.13| 4.44| |P. E. of σ | ±.61| ±.38| ±.59| ±.17| ±.11| ±.16| ±.36| +--------------+-----+-----+-----+-----+-----+-----+-----+

+--------------+-----+-----+-----+-----+-----+-----+------+ | Serial | X | XI | XII | XIII| XIV | XV | | | mating No. | | | | | | | | +--------------+-----+-----+-----+-----+-----+-----+ | | Type of | M | M | M | F | F | VF | | | mating. | × | × | × | × | × | × |Total.| | | M | F | VF | F | VF | VF | | +--------------+-----+-----+-----+-----+-----+-----+ | | Av. index | | | | | | | | | of build | 33.2| 36.4| 40.7| 39.2| 43.0| 47.4| | +--------------+-----+-----+-----+-----+-----+-----+------+ | No. of | | | | | | | | | matings. | 92 | 114 | 30 | 33 | 29 | 7 | 506 | +--------------+-----+-----+-----+-----+-----+-----+------+ | 22 | | | | | | | 2 | | 23 | | | | | | | 2 | | 24 | | | | | | | 0 | | 25 | 2 | | 2 | | | | 12 | | 26 | | 1 | | 1 | | | 16 | | 27 | 4 | | 1 | | 1 | | 24 | | 28 | 2 | 4 | | 2 | | | 30 | | 29 | 10 | 7 | 3 | 8 | | | 59 | | 30 | 23 | 16 | 3 | 4 | 2 | | 86 | | 31 | 25 | 15 | 6 | 4 | 4 | 2 | 119 | | 32 | 30 | 40 | 9 | 6 | 6 | 4 | 159 | | 33 | 37 | 46 | 8 | 4 | 9 | 1 | 178 | | 34 | 28 | 34 | 12 | 12 | 5 | 3 | 143 | | 35 | 34 | 33 | 12 | 17 | 8 | 2 | 154 | | 36 | 44 | 40 | 3 | 17 | 6 | 2 | 142 | | 37 | 22 | 22 | 9 | 13 | 3 | 1 | 102 | | 38 | 17 | 23 | 5 | 11 | 8 | | 93 | | 39 | 18 | 10 | 11 | 7 | 8 | 2 | 79 | | 40 | 9 | 12 | 5 | 10 | 6 | 2 | 58 | | 41 | 9 | 11 | 2 | 3 | 3 | | 38 | | 42 | 3 | 7 | 1 | 11 | 9 | 1 | 42 | | 43 | 3 | 3 | 3 | 6 | 5 | | 29 | | 44 | | 3 | 1 | 6 | 3 | 1 | 18 | | 45 | 1 | 2 | 6 | 2 | 3 | 2 | 20 | | 46 | 1 | 1 | 3 | | 3 | 1 | 12 | | 47 | 1 | 4 | | 5 | 2 | 3 | 16 | | 48 | | | 1 | | 3 | | 5 | | 49 | 2 | 1 | 1 | 2 | | | 7 | | 50 | | 1 | 2 | | | 2 | 6 | | 51 | 1 | | | 2 | 1 | 1 | 7 | | 52 | | | 1 | 1 | | | 2 | | 53 | | 2 | | 2 | 2 | | 6 | | 54 | | 1 | | | | | 1 | | 55 | | | | | | | 0 | | 56 | 1 | | | | | | 1 | | 57 | | | | | | | 0 | | 58 | | 1 | | | | | 1 | | 79 | | | 1 | | | | 1 | | 103 | | | 1 | | | | 1 | | Total | 327 | 340 | 112 | 156 | 100 | 30 | 1671 | +--------------+-----+-----+-----+-----+-----+-----+------+ |Adult progeny | | | | | | | | | per mating | 3.55| 2.98| 3.70| 4.72| 3.45| 4.29| 3.29 | |Average |34.79|35.41|37.64|37.56|38.49|39.20|35.24 | |P. E. of aver.| ±.15| ±.16| ±.58| ±.29| ±.38| ±.78| ±.087| |σ | 4.05| 4.34| 9.11| 5.37| 5.38| 6.31| 5.29 | |P. E. of σ | ±.11| ±.11| ±.41| ±.21| ±.27| ±.55| ±.06 | +--------------+-----+-----+-----+-----+-----+-----+------+

MASS STUDY OF VARIATION AND HEREDITY IN BUILD.

Having considered the classification and something of the causes of variation in build, we have now to consider the relation between the build of the parents and that of the progeny. This is the mass treatment of the data of “heredity” which was the prevailing method 25 years ago and earlier. It is still a useful method in the case of traits due to multiple factors, such as the present one.

The distribution of build in the children of the different matings is given in tables 11, 11A, and 12. There are 15 possible different combinations of matings of the five grades. The first of these (VS × VS) is not represented in our data, and the fifth, VS × VF, is represented by only one mating and no column is devoted to it. The frequencies are given separately for male and female offspring (table 11), and again for both sexes together (table 12). Table 13 shows that there is a considerable correlation between the average build of the parentage and that of the progeny. From the matings of the fleshier parents the progeny are fleshier; from those of slender parents, slenderer. This relation may conceivably be due to family tradition handed down from parents to children. We shall see later that this hypothesis meets with formidable difficulties to acceptance. The most reasonable hypothesis is that there are, above all, hereditary family tendencies that help determine build.

TABLE 13.—Distribution of progeny of the various matings, according to classes of build, absolute numbers, and proportions, based on Appendix table, including starred families.

+----------------+-----------+---------------------+-------------------+ | | | | Proportional | | | Total | Absolute numbers. | frequencies | |Type of mating. | No. of | | (per mille). | | | children. +----+---+----+---+---+---+---+---+---+---+ | | |VS. | S.| M. | F.|VF.|VS.| S.| M.| F.|VF.| +----------------+-----------+----+---+----+---+---+---+---+---+---+---+ |No. II VS × S | 20 | 4 | 12| 2| 2| |200|600|100|100| | | III VS × M | 28 | 1 | 7| 17| 3| | 36|250|607|107| | | IV VS × F | 25 | 1 | 5| 10| 7| 2| 40|200|400|280| 80| | VI S × S | 51 | 5 | 35| 11| | | 98|686|215| | | | VII S × M | 313 | | 49| 200| 53| 11| |157|639|169| 35| | VIII S × F | 179 | 5 | 25| 85| 57| 7| 28|140|475|318| 39| | IX S × VF | 50 | | 7| 18| 17| 8| |140|360|340|160| | X M × M | 332 | 2 | 40| 201| 82| 7| 6|121|605|247| 21| | XI M × F | 346 | | 31| 210| 88| 17| | 90|606|255| 49| | XII M × VF | 112 | 2 | 7| 50| 36| 17| 18| 63|446|321|152| | XIII F × F | 159 | | 15| 62| 61| 21| | 94|390|384|132| | XIV F × VF | 146 | 1 | 7| 52| 51| 35| 7| 48|356|349|240| | XV VF × VF | 37 | | | 12| 8| 10| | |400|267|333| | +-----------+----+---+----+---+---+---+---+---+---+---+ | Total | 1798 | | | | | | | | | | | +----------------+-----------+----+---+----+---+---+---+---+---+---+---+

Comparing the tables for male and female offspring, it appears, first, that there are, for some reason, more males than females about whom data of build are given, probably because more males than females know their stature and weight, or willingly record it; second, there are relatively more females than males of very slender build (grades 22 to 31); there are recorded relatively more very fleshy males than females (grades of 50 and above); third, there are relatively more recorded daughters than sons derived from one very slender parent, and from the F × F and M × M matings. The male progeny are more variable than the female as 5.325 ± 0.084 is to 5.133 ± 0.089; but the difference is less than three times the probable error, and is, consequently, not very significant.

Considering next the table of total progeny of the various matings, it appears that the average number of children with recorded build from the recorded matings is variable. In descending order the fecundity of the matings is shown in table 14. This table shows that larger families, on the average, were derived from fleshy parents than from slender parents. Thus the F × F matings yield 2.3 times as many children, on the average, per mating as the S × S matings.

TABLE 14.—Average number of progeny yielded by each type of mating (based on table 12).

+-------+---------+-------+---------+ |Mating.| No. of |Mating.| No. of | | |children.| |children.| +-------+---------+-------+---------+ |VS × F | 5.00 | S × F | 3.16 | | F × F | 4.72 | S × VF| 3.09 | |VF × VF| 4.29 | S × M | 3.03 | | M × VF| 3.70 | M × F | 2.98 | | M × M | 3.55 |VS × S | 2.75 | |VS × M | 3.50 | S × S | 2.04 | | F × VF| 3.45 | | | +-------+---------+-------+---------+

REGRESSION OF PROGENY TOWARD MEDIOCRITY.

Galton pointed out, in the case of stature, that, since correlation between parents and progeny is not perfect, the progeny of selected parents will tend to be less extremely selected and hence more nearly mediocre than their parents. It has, indeed, been shown in my studies on stature (1917, p. 341) that the progeny of tall parents do not show this regression to mediocrity as much as the progeny of short parents. This was regarded as evidence that the gametes of tall parents carried fewer recessive allelomorphs than those of short parents; hence were genetically “purer” and comprise more recessive factors. What is the condition in respect to the varying indices of build?

The answer to this question is given in table 15, which in turn is based on table 12. This table shows for each of the 13 matings the average departure of the parents from mediocre build (which for the parents is 34.86) and the corresponding departure of their offspring from mediocre build (which for the progeny is 35.24). In the right-hand column of the table is given the difference between these two departures, which measures the amount of regression toward mediocrity on the part of the progeny. The results of the last column are shown graphically in figure 8.

TABLE 15.—Average build and regression from parental average of the progeny of the various types of mating. Also matings arranged in order of regression. Sexes combined (based on table 12).

+-------+--------+--------+--------+-----------+-------+-------+-------+ | | | | | | | Regression.| | | | | Avg. | | Departure of | | |Type of| No. of | No. of | build |Avg. build |parents|progeny| | |mating.|matings.|progeny.| of |of progeny.| from | | | | | |parents.| | mediocrity. | | +-------+--------+--------+--------+-----------+-------+-------+-------+ |VS × S | 4 | 11 | 26.13 |28.55 ± .86| -8.73 | -6.69 | +2.04 | |VS × M | 8 | 28 | 28.38 |32.18 ± .54| -6.48 | -3.06 | +3.42 | |VS × F | 5 | 25 | 32.00 |35.04 ± .83| -2.86 | -0.20 | +2.66 | | S × S | 23 | 47 | 29.77 |28.47 ± .24| -5.09 | -6.77 | -1.68 | | S × M | 101 | 306 | 30.90 |34.01 ± .16| -3.96 | -1.23 | +2.73 | | S × F | 49 | 155 | 33.85 |34.39 ± .22| -1.01 | -0.85 | +0.16 | | S × VF| 11 | 34 | 37.91 |35.48 ± .51| +3.05 | +0.24 | +2.81 | | M × M | 92 | 327 | 33.23 |34.79 ± .15| -1.63 | -0.45 | +1.18 | | M × F | 114 | 340 | 36.45 |35.41 ± .16| +1.59 | +0.17 | +1.42 | | M × VF| 30 | 112 | 40.68 |36.53 ± .38| +5.82 | +1.29 | +4.53 | | F × F | 33 | 156 | 39.21 |37.56 ± .29| +4.35 | +2.32 | +2.03 | | F × VF| 30 | 100 | 42.97 |38.49 ± .36| +8.11 | +3.25 | +4.86 | |VF × VF| 7 | 30 | 47.43 |39.20 ± .78| +12.57| +3.96 | +8.61 | | +--------+--------+--------+-----------+-------+-------+-------+ | Total | 507 | 1671 | 34.86 |35.24 | | | | +-------+--------+--------+--------+-----------+-------+-------+-------+

Mediocrity for parents, 34.86. Mediocrity for progeny, 35.24.

MATINGS ARRANGED IN ORDER OF REGRESSION.

+---------+-------+ | S × S | -1.68 | | S × F | +0.16 | | M × M | +1.18 | | M × F | +1.42 | | F × F | +2.03 | | VS × S | +2.04 | | VS × F | +2.66 | | S × M | +2.73 | | S × VF | +2.81 | | VS × M | +3.42 | | M × VF | +4.53 | | F × VF | +4.86 | | VF × VF | +8.61 | +---------+-------+

Figure 8 shows clearly that, in spite of considerable irregularities, the line of regression descends from the matings of two very fleshy parents at the left, and in general from matings in which the average parental departure from the mean build of parents is positive, to the mating of two slender parents (or, less strikingly the VS × S mating) or in general to the matings in which the average parental departure is extremely negative. This result is most easily explained on the ground that whereas fleshy parents carry all sorts of gametes for build, slender parents carry a preponderance of gametes of their own kind; hence the progeny do not regress so much from the selected parental condition. This suggests that the slender parents are more nearly homozygous than the fleshy parents.

Still another test of the gametic composition of the parents is the variability of their offspring. The facts regarding such variability are given in table 16. From this table it appears that the mating that yields the least variable progeny is that of two slender consorts. The variability in their progeny is measured by 2.41 ± 0.17. The variability of the progeny of the VS × S mating is greater, 4.21 ± 0.61, but on account of the small number of the progeny the probable error is large, and it is possible that this difference in variability between S × S and VS × S progeny is not a significant one. Next to the least variable are the offspring of the M × M mating, 4.06 ± 0.11, and this leads to the conclusion that a large proportion of the M parents are not merely heterozygous, but constitute a “pure race” of medium build. The offspring of the S × F mating have a fairly small variability 4.13 ± 0.16, as befits a first generation (F₁) hybrid. On the other extreme, we have the M × VF mating with a standard deviation of 9.11 ± 0.41. This large standard deviation is due chiefly to the inclusion of one family (Ber-A) which contains 2 progeny of builds 79 and 103, weighing 180 kg. (400 pounds) and 215 kg. (475 pounds) respectively. Otherwise, the variability of this mating is not extreme. It is 5.25 ± 0.24. The next largest variability is from the VF × VF mating, 6.31 ± 0.55, a variability that is due to the absence of any important mode. The progeny of the VS × F mating are highly variable, 6.18 ± 0.59, but this standard deviation has the largest probable error of any except VS × S, so that great stress must not be laid upon its exact position. In general, the progeny of matings with 2 or 1 F or VF parents, belong to the more variable group and those with S (or VS) parents to the less variable group. The meaning of this is clear to the geneticist who has dealt with multiple factors. It indicates that some or all of the factors that make for fleshy build dominate to a greater or less degree over the factors for slenderness. The test of the regression of progeny toward mediocrity and the test of the variability of the progeny of the various matings thus lead to the same result—the factors for fleshiness are imperfectly dominant over those for slenderness, and the latter probably lack some or all of those factors that make for fleshy build.

TABLE 16.—Progeny of the various types of matings arranged in order of variability or standard deviation (S. D.), together with the probable errors (P. E.) of the means and deviations; also the coefficients of variation (based on table 12).

+-------+--------+-------------------+------------------+--------------+ |Type of| No. of | Mean build of |Standard deviation|Coefficient of| |mating.|progeny.|progeny and (P. E.)| and (P. E.) | variability. | +-------+--------+-------------------+------------------+--------------+ | S × S | 47 | 28.47 ± 0.24 | 2.41 ± 0.17 | 8.97 | | M × M | 327 | 34.79 ± 0.15 | 4.06 ± 0.11 | 11.67 | | S × F | 155 | 34.39 ± 0.22 | 4.13 ± 0.16 | 12.01 | | S × M | 306 | 34.01 ± 0.16 | 4.20 ± 0.11 | 12.35 | |VS × S | 11 | 28.55 ± 0.86 | 4.21 ± 0.61 | 14.75 | |VS × M | 28 | 32.18 ± 0.54 | 4.22 ± 0.38 | 13.11 | | M × F | 340 | 35.41 ± 0.16 | 4.27 ± 0.11 | 12.06 | | S × VF| 34 | 35.68 ± 0.51 | 4.44 ± 0.36 | 12.44 | | F × F | 157 | 37.56 ± 0.29 | 5.37 ± 0.20 | 14.30 | | F × VF| 100 | 38.49 ± 0.36 | 5.38 ± 0.27 | 3.98 | |VS × F | 25 | 35.04 ± 0.83 | 6.18 ± 0.59 | 17.64 | |VF × VF| 30 | 39.20 ± 0.78 | 6.31 ± 0.55 | 16.10 | | M × VF| 112 | 37.64 ± 0.58 | 9.11 ± 0.41 | 24.17 | +-------+--------+-------------------+------------------+--------------+

HYPOTHESIS.

The foregoing brief studies of the progeny of classes of matings suggest the following hypothesis:

Fleshy build results from the action of several positive (dominant) factors that make for stoutness, while slenderness results from the absence of one or more of such factors, or is due to recessive factors. Fleshy parents may, and frequently do, carry gametes which lack the “fleshy” or carry the “slender” factor, while in slender parents for the most part the gametes carry only the slender factor, hence the gametes of slender parents are more nearly homogeneous. This hypothesis may be further developed as follows:

Assuming that there are two independent factors A and B for build, then these may be found in different zygotes in the following combinations:

AABB AaBB aABB aaBB AABb AaBb aABb aaBb AAbB AabB aAbB aabB AAbb Aabb aAbb aabb

Or, disregarding order of the letters, and considering only the number and kind of genes in each kind of zygote, we have:

AABB 2AaBB aaBB 2AABb 4AaBb 2aaBb AAbb 2Aabb aabb

in which the coefficients indicate the relative frequency of the different combinations.

We may assume that:

4 positive factors in a zygote correspond to a very fleshy person. 3 factors correspond to a fleshy person. 2 factors correspond to a person of medium build. 1 factor corresponds to a slender person. 0 factor corresponds to a very slender person.

Table 17 indicates the possible matings and their progeny.

TABLE 17.—Percentage distribution of the progeny of the various matings, on the assumption that extreme fleshy build is dependent upon 4 zygotic factors in the parents.

+-----+-----+-------------+-----------+-------------------------------+ | | | | | Percentage of each number of | |One |Other| Zygotic | Gametic | zygotes in progeny. | | parent. | formulæ. | formulæ. +------+-----+-----+-----+------+ | | | | |0 (VS)|1 (S)|2 (M)|3 (F)|4 (VF)| +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | 4 | 4 | AABB × AABB | AB × AB | | | | | 100 | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | 4 | 3 | AABB × AABb |{ AB × AB }| | | | 50 | 50 | | | | |{ AB × Ab }| | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | | | AABB × AAbb | AB × Ab | | | | 100 | | | | | | | | | | | | | 4 | 2 | |{ AB × AB }| | | | | | | | | AABB × AaBb |{ AB × Ab }| | | 25 | 50 | 25 | | | | |{ AB × aB }| | | | | | | | | |{ AB × ab }| | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | 4 | 1 | AABB × Aabb |{ AB × Ab }| | | 50 | 50 | | | | | |{ AB × ab }| | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | 4 | 0 | AABB × aabb | AB × ab | | | 100 | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | | | |{ AB × AB }| | | | | | | 3 | 3 | AABb × AABb |{ AB × Ab }| | | 25 | 50 | 25 | | | | |{ Ab × AB }| | | | | | | | | |{ Ab × Ab }| | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | 3 | 2 | AABb × AAbb |{ AB × Ab }| | | 50 | 50 | | | | | |{ Ab × Ab }| | | | | | | | | | | | | | | | | | | |{ AB × AB }| | | | | | | | | |{ AB × Ab }| | | | | | | | | |{ AB × aB }| | | | | | | | | |{ AB × ab }| | | | | | | | | AABb × AaBb |{ Ab × AB }| | 12.5| 37.5| 37.5| 12.5| | | | |{ Ab × Ab }| | | | | | | | | |{ Ab × aB }| | | | | | | | | |{ Ab × ab }| | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | | | |{ AB × Ab }| | | | | | | 3 | 1 | AABb × Aabb |{ AB × ab }| | 25 | 50 | 25 | | | | | |{ Ab × Ab }| | | | | | | | | |{ Ab × ab }| | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | | | |{ AB × ab }| | | | | | | 3 | 0 | AABb × aabb |{ Ab × ab }| | 50 | 50 | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | | | AAbb × AAbb | Ab × Ab | | |100 | | | | | | | | | | | | | | | | |{ Ab × AB }| | | | | | | | | AAbb × AaBb |{ Ab × Ab }| | 25 | 50 | 25 | | | | | |{ Ab × aB }| | | | | | | | | |{ Ab × ab }| | | | | | | | | | | | | | | | | | | |{ AB × Ab }| | | | | | | | | AaBb × AAbb |{ Ab × Ab }| | 25 | 50 | 25 | | | | | |{ aB × Ab }| | | | | | | | | |{ ab × Ab }| | | | | | | 2 | 2 | | | | | | | | | | | |{ AB × AB }| | | | | | | | | |{ AB × Ab }| | | | | | | | | |{ AB × aB }| | | | | | | | | |{ AB × ab }| | | | | | | | | |{2Ab × AB }| | | | | | | | | AaBb × AaBb |{2Ab × Ab }| 6.25| 25 | 37.5| 25 | 6.25| | | | |{2Ab × aB }| | | | | | | | | |{2Ab × ab }| | | | | | | | | |{ ab × AB }| | | | | | | | | |{ ab × Ab }| | | | | | | | | |{ ab × aB }| | | | | | | | | |{ ab × ab }| | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | | | |{ Ab × Ab }| | | | | | | | | AAbb × Aabb |{ Ab × ab }| | 50 | 50 | | | | | | | | | | | | | | | | |{ AB × Ab }| | | | | | | | | |{ Ab × Ab }| | | | | | | 2 | 1 | |{ AB × ab }| | | | | | | | | AABb × Aabb |{ Ab × ab }| 12.5| 37.5| 37.5| 12.5| | | | | |{ aB × Ab }| | | | | | | | | |{ aB × aB }| | | | | | | | | |{ ab × Ab }| | | | | | | | | |{ ab × ab }| | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | | | AAbb × aabb | Ab × ab | |100 | | | | | | | | | | | | | | | | | |{ AB × ab }| | | | | | | 2 | 0 | AaBb × aabb |{ Ab × ab }| 25 | 50 | 25 | | | | | | |{ aB × ab }| | | | | | | | | |{ ab × ab }| | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | | | |{ Ab × Ab }| | | | | | | 1 | 1 | Aabb × Aabb |{ AB × ab }| | 50 | 50 | | | | | | |{ ab × Ab }| | | | | | | | | |{ ab × ab }| | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | 1 | 0 | Aabb × aabb |{ Abab }| 50 | 50 | | | | | | | |{ abab }| | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+ | 0 | 0 | aabb × aabb | | 100 | | | | | +-----+-----+-------------+-----------+------+-----+-----+-----+------+

On the hypothesis of 6 zygotic factors for build, the possible combinations in the progeny are much more numerous. Seven classes of zygotic combinations are possible. We recognize in our work only 5 classes of build. Accordingly, it would be necessary to redistribute our classes of build into 7 or else assume that the two lowest classes are both comprised in “very slender” and the two highest in “very fleshy.” The former operation would require an amount of work hardly justified by the possible advantage; so the latter procedure was adopted as perhaps a sufficiently close approximation. The distributions are given in table 18 which is given in detail only in part.

TABLE 18.—Percentage distribution of the progeny of the various matings on the assumption that extreme fleshy build is dependent on 6 zygotic factors in the parents.

+----------+-----------------------------------------------------------+ | No. of | | |factors in| Percentage of each class of zygotic factors. | +----+-----+---------+-------+--------+------+--------+-------+--------+ |One |Other| 6 | 5 | 4 | 3 | 2 | 1 | 0 | | parent. | | | | | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 6 | 6 | 100 | | | | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 6 | 5 | 50 | 50 | | | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 6 | 4 |{ |100 | | | | | | | | |{ 25 | 50 | 25 | | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 6 | 3 |{ | 50 | 50 | | | | | | | |{ 12.5 | 37.5 | 37.5 | 12.5 | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 6 | 2 |{ | |100 | | | | | | | |{ | 25 | 50 | 25 | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 6 | 1 | | | 50 | 50 | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 6 | 0 | | | |100 | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 5 | 5 | 25 | 50 | 25 | | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 5 | 4 |{ | 50 | 50 | | | | | | | |{ 12.5 | 37.5 | 37.5 | 12.5 | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 5 | 3 |{ 6.25 | 25 | 37.5 | 25 | 6.25 | | | | | |{ | 25 | 50 | 25 | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 5 | 2 |{ | 12.5 | 37.5 | 37.5 | 12.5 | | | | | |{ | | 50 | 50 | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 5 | 1 | | | 25 | 50 | 25 | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 5 | 0 | | | | 50 | 50 | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | | |{ 6.25 | 25 | 37.5 | 25 | 6.25 | | | | 4 | 4 |{ | 25 | 50 | 25 | | | | | | |{ | 25 | 50 | 25 | | | | | | |{ | |100 | | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | | |{ 3.125 | 15.625| 31.25 | 31.25| 15.625 | 3.125| | | 4 | 3 |{ | 12.5 | 37.5 | 37.5 | 12.5 | | | | | |{ | 12.5 | 37.5 | 37.5 | 12.5 | | | | | |{ | | 50 | 50 | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | | |{ | 6.25 | 25 | 37.5 | 25 | 6.25 | | | 4 | 2 |{ | | 25 | 50 | 25 | | | | | |{ | | 25 | 50 | 25 | | | | | |{ | | |100 | | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 4 | 1 |{ | | | 50 | 50 | | | | | |{ | | 12.5 | 37.5 | 37.5 | 12.5 | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 4 | 0 | | | | 25 | 50 | 25 | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | | |{ 1.5625| 9.375| 23.4375| 31.25| 23.4375| 9.375| 1.5625| | 3 | 3 |{ | 6.25 | 25 | 37.5 | 25 | 6.25 | | | | |{ | 6.25 | 25 | 37.5 | 25 | 6.25 | | | | |{ | | 25 | 50 | 25 | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | | |{ | 3.125| 16.625 | 31.25| 31.25 | 16.625| 3.125 | | 3 | 2 |{ | | 12.5 | 37.5 | 37.5 | 12.5 | | | | |{ | | 12.5 | 37.5 | 37.5 | 12.5 | | | | |{ | | | 50 | 50 | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 3 | 1 |{ | | 6.25 | 25 | 37.5 | 25 | 6.5 | | | |{ | | | 25 | 50 | 25 | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 3 | 0 |{ | | | 12.5 | 37.5 | 37.5 | 12.5 | | | |{ | | | | 50 | 50 | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | | |{ | | 6.25 | 25 | 37.5 | 25 | 6.25 | | 2 | 2 |{ | | | | 50 | 50 | | | | |{ | | | |100 | | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 2 | 1 |{ | | | 12.5 | 37.5 | 37.5 | 12.5 | | | |{ | | | | 50 | 50 | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 2 | 0 |{ | | | | 25 | 50 | 25 | | | |{ | | | | |100 | | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 1 | 1 | | | | | 25 | 50 | 25 | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 1 | 0 | | | | | | 50 | 50 | +----+-----+---------+-------+--------+------+--------+-------+--------+ | 0 | 0 | | | | | | |100 | +----+-----+---------+-------+--------+------+--------+-------+--------+

MATE SELECTION IN BUILD.

Statistics on temperament and stature of consorts (Davenport, 1915, p. 106; 1917, p. 329) seem clearly to show that there is an assortative mating in respect to these traits. The question arises: Is there assortative mating in respect to build? The inquiry is rendered the more difficult, inasmuch as build changes to such an extent with age. Nevertheless, as there appears to be a considerable correlation (though not yet calculated) between build at 25 and at 50 years, it is fair to assume that some degree of the mature build is already indicated at the period just before marriage.

If, now, there is no assortative mating in respect to build, we should find that persons of any given build, say slender, would have very slender, slender, medium, fleshy, and very fleshy consorts in the respective proportions in which such classes of build occur in the whole population of parents. A marked deviation from this expectation would indicate the falseness of this hypothesis and that there is an assortative mating in respect to build.

To test the hypothesis we can make use of 531 matings, including those which are employed in the main tables. We find the male and the female consorts in these matings to occur in the different classes in the numbers and proportions shown in table 19.

TABLE 19.—Percentage distribution of parents of each sex among the various classes of build as found in 531 selected matings. Based on Appendix tables.

+----------+----------------------+----------------------+ | | Males. | Females. | | +----------+-----------+----------+-----------+ | Classes. | | | | | | |Frequency.| Per cent. |Frequency.| Per cent. | +----------+----------+-----------+----------+-----------+ | VS | 22 | .38 | 18 | 3.39 | | S | 97 | 18.27 | 127 | 23.92 | | M | 230 | 43.31 | 210 | 39.55 | | F | 158 | 29.75 | 120 | 22.59 | | VF | 44 | 8.29 | 56 | 10.55 | | +----------+-----------+----------+-----------+ | Total | 531 | 100 | 531 | 100 | +----------+----------+-----------+----------+-----------+

In applying the test to the hypothesis we may assume in turn that the groom has done the selecting and that the bride has done the selecting. We then compare, in the selections made by the grooms, the expected proportion of the classes of build on the assumption of no assortative mating, with the proportions actually found in the brides. Similarly, with suitable changes for the selections made by the brides. The results are given in table 20.

TABLE 20.—Percentage distribution of build of consorts selected by grooms and by brides belonging to each of the classes of build, and comparison with the standards of table 19.

P, percentages found or expected. E, percentage excess of found over expected.

+----------+-----------+----------+----------+----------+----------+---+ | | | | | | | T | | | VS | S | M | F | VF | o | | | | | | | | t | | +----+------+----+-----+----+-----+----+-----+----+-----+ a | | | P | E | P | E | P | E | P | E | P | E | l | +----------+----+------+----+-----+----+-----+----+-----+----+-----+---+ | SELECTIONS MADE BY GROOMS. | +----------+----+------+----+-----+----+-----+----+-----+----+-----+---+ |Expected | | | | | | | | | | | | | build | | | | | | | | | | | | | of | | | | | | | | | | | | | brides, | | | | | | | | | | | | | random | | | | | | | | | | | | | selection|3.4 | |23.9| |39.6| |22.6| |10.6| |100| | | | | | | | | | | | | | |Selections| | | | | | | | | | | | | by | | | | | | | | | | | | | slender| | | | | | | | | | | | | grooms |5.2 | +52.9|24.7| +3.3|37.1| +6.3|23.7| +4.9| 9.3|-12.3| | | | | | | | | | | | | | | |Selections| | | | | | | | | | | | | by | | | | | | | | | | | | | medium | | | | | | | | | | | | | grooms |3.5 | +2.9 |28.3|+18.4|40.4| +2.0|22.3| -1.3| 5.6|-47.2| | | | | | | | | | | | | | | |Selections| | | | | | | | | | | | | by | | | | | | | | | | | | | fleshy | | | | | | | | | | | | | grooms |3.2 | -5.9 |18.3|-23.4|40.5| +2.3|21.5| -4.9|16.5|+55.7| | | | | | | | | | | | | | | |Selections| | | | | | | | | | | | | by very | | | | | | | | | | | | | fleshy | | | | | | | | | | | | | grooms |0.0 | -100 |15.9|-33.5|38.6| -2.5|27.3|+20.8|18.2|+71.7| | | | | | | | | | | | | | | +----------+----+------+----+-----+----+-----+----+-----+----+-----+---+ | SELECTIONS MADE BY BRIDES. | +----------+----+------+----+-----+----+-----+----+-----+----+-----+---+ | | | | | | | | | | | | | |Expected | | | | | | | | | | | | | build | | | | | | | | | | | | | of | | | | | | | | | | | | | grooms, | | | | | | | | | | | | | random | | | | | | | | | | | | | selection|0.4 | |18.3| |43.3| |29.8| | 8.3| |100| | | | | | | | | | | | | | |Selections| | | | | | | | | | | | | by | | | | | | | | | | | | | slender| | | | | | | | | | | | | brides |1.59|+297.5|18.9| +3.3|51.2|+18.2|22.8|-23.5| 5.5|-33.7| | | | | | | | | | | | | | | |Selections| | | | | | | | | | | | | by | | | | | | | | | | | | | medium | | | | | | | | | | | | | brides |0.0 | -100 |17.1| -6.6|44.3| +2.3|30.5| +2.3| 8.1| -2.4| | | | | | | | | | | | | | | |Selections| | | | | | | | | | | | | by | | | | | | | | | | | | | fleshy | | | | | | | | | | | | | brides |0.0 | -100 |19.2| +4.9|42.5| -1.8|28.3| -5.0|10.0|+20.5| | | | | | | | | | | | | | | |Selections| | | | | | | | | | | | | by very | | | | | | | | | | | | | fleshy | | | | | | | | | | | | | brides |0.0 | -100 |16.1|-12.0|23.2|-46.4|46.4|+55.7|14.3|+72.3| | | | | | | | | | | | | | | +----------+----+------+----+-----+----+-----+----+-----+----+-----+---+

An inspection of tables 19 and 20 shows that the hypothesis that wives and husbands of men of each different class of build are merely random samples of the whole population of parents is not supported by the facts. Thus on the part of both very fleshy grooms and brides over 70 per cent more consorts, who will ultimately be very fleshy are selected than are expected on the hypothesis of random sampling. Also, among fleshy fathers there is a marked excess of very fleshy wives. Slender parents have an excess of similar consorts. Medium parents have selected consorts nearly at random so far as regards build. Slender parents have selected a smaller proportion of very fleshy consorts than expectation on random choice, and very fleshy parents have selected less than the average of very slender and slender consorts. In a word, there is some degree of assortative mating and, indeed, a mating of similars. This result agrees with the findings in respect to stature; similars tend to mate; while in the case of temperament, dissimilars tend to marry each other.

THE BASAL TABLES.

In the Appendix are given in tabular form details concerning the different types of matings, with some information concerning the grandparents, the sibs of parents, and the children. These are the tables that have been used for the mass study and from which table 11 was drawn up. They will afford much of our data for the detailed Mendelian studies, and will be briefly considered in this section.

The families in the tables of the Appendix which are marked by an asterisk (*) are not included in table 11. The reason is that they were selected families, usually because containing very fleshy persons. It was deemed undesirable to combine these selected families with the unselected families that make up most of table 11; a table which forms the basis for figure 7. To have included them would have distorted the form of that figure.

These tables are derived chiefly from the Records of Family Traits; some from special schedules and, in a few cases, from the A file of the Eugenics Record Office.

Table I.—Mating of very slender, 1.50 to 1.75 metric (21 to 25 English) × very slender. This combination does not occur in our 506 standard matings.

Table II.—Matings of very slender × slender, 1.80 to 2.10 (26 to 30). There are seven matings altogether. They yielded 20 progeny: 4 VS, 12 S, 2 M, and 2 F. Four-fifths of the progeny thus fall in the parental groups; the distribution shows little variability (fig. 9).

Table III.—Matings of very slender × medium, 2.2 to 2.6 (31 to 36). 28 children derived from 8 matings have indices of build as follows: 1 VS, 7 S, 17 M, 3 F. The mode of the progeny, as compared with table 2, has shifted to the medium grade (fig. 10).

Table IV.—Matings of very slender × fleshy, 2.6 to 3.0 (37 to 43). There are 5 matings. These yielded 25 progeny: 1 VS, 5 S, 10 M, 7 F, and 2 VF. The mode is at medium grade, but the whole distribution is much more variable than in tables 2 and 3 (fig. 11).

Table V.—Matings of very slender × very fleshy, 3.1 to 4.5 (44 to 64). There is only 1 mating in this class, so that no table is formed. It is described in full on page 97. It produced 7 children: 3 S, 3 M, and 1 VF.

Table VI.—Matings of slender × slender. There are 24 matings of this type. They yielded 51 progeny: 5 VS, 35 S, 11 M. The mode is strongly in the S grade; the progeny show relatively little variability (fig. 12).

Table VII.—Matings of slender × medium parents. There are 101 matings of this type. They yielded 313 progeny: 49 S, 200 M, 53 F, 11 VF. The mode is at medium; the progeny show rather low variability (fig. 13).

Table VIII.—Matings of slender × fleshy parents. There are 52 matings of this type. They yielded 179 progeny: 5 VS, 25 S, 85 M, 57 F, 7 VF. The mode is at medium: the progeny show rather low variability (fig. 14).

Table IX.—Matings of slender × very fleshy parents. There are 16 matings of this type. They yielded 50 progeny: 7 S, 18 M, 17 F, 8 VF. The progeny are very variable (fig. 15).

Table X.—Matings of medium × medium parents. There are 93 matings of this type. They yielded 332 offspring: 2 VS, 40 S, 201 M, 82 F, 7 VF. The progeny are not very variable (fig. 16), indicating that all individuals of medium build are not “heterozygotes”; but that there is also a “medium” race.

Table XI.—Matings of medium × fleshy parents. There are 115 matings of this type. They yielded 346 offspring: 31 S, 210 M, 88 F, 17 VF. The progeny show an intermediate degree of variability (fig. 17).

Table XII.—Matings of medium × very fleshy parents. There are 30 matings of this type. They yielded 112 offspring: 2 VS, 7 S, 50 M, 36 F, 17 VF. The progeny show considerable variability (fig. 18).

Table XIII.—Matings of fleshy × fleshy parents. There are 33 matings of this type. They yielded 159 offspring: 15 S, 62 M, 61 F, 21 VF. The progeny show a rather high variability (fig. 19).

Table XIV.—Matings of fleshy × very fleshy parents. There are 30 matings of this type. They yielded 146 offspring: 1 VS, 7 S, 52 M, 51 F, 35 VF. The progeny are very variable (fig. 20).

Table XV.—Matings of very fleshy × very fleshy parents. There are 7 matings of this type. They yielded 37 offspring: 1 S, 12 M, 11 F, 13 VF. The progeny are exceedingly variable (fig. 21).

The diversity of the distributions of the progeny of the various matings and the great difference in their variabilities indicates that there is not only an inheritance of tendencies to particular types of build, but also that there is a strong evidence of some sort of Mendelian inheritance.