QH 
 431 
 C265
 
 GENETIC STUDIES OF RABBITS 
 AND RATS 
 
 BY 
 
 W. E. CASTLE 
 
 PUBLISHED BY THE CARNEGIE INSTITUTION OF WASHINGTON 
 WASHINGTON, MAY, 1922
 
 ^GENETIC STUDIES OF RABBITS 
 AND RATS 
 
 BY 
 
 W. E. CASTLE 
 \> 
 
 PUBLISHED BY THE CARNEGIE INSTITUTION OF WASHINGTON 
 WASHINGTON, MAY, 1922 
 
 BL*
 
 CARNEGIE INSTITUTION OF WASHINGTON 
 PUBLICATION No. 320 
 
 Copies of this book 
 
 first issued 
 MAY 2 21922 
 
 TECHNICAL PRESS 
 WASHINGTON, D. C.
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 PART I. 
 
 SIZE-INHERITANCE IN RABBIT CROSSES. 
 
 In the last fifteen years numerous studies have been made of the 
 inheritance of characters which are quantitatively variable or fluc- 
 tuating. As a result of these studies it has become clear that in 
 many cases fluctuation is due to non-genetic causes, to the environ- 
 ment rather than to the constitution of the germ-cells. In such 
 cases selection is without effect in modifying the racial character. 
 This is the accepted explanation of the negative results obtained by 
 Johannsen in selecting beans for increased or decreased size, and of 
 the similar results of Ewing in selecting plant-lice for altered body 
 dimensions, and those of Jennings and others with paramecium. 
 
 But in a majority of cases variation due to genetic causes occurs 
 in association with that due to non-genetic or environmental causes; 
 in fact, it is possible to distinguish between the two only by the 
 results of systematic selection. When the environment is kept 
 constant and a race does not change in response to selection, we 
 assume that no genetic variation is present. But if the race does 
 change in response to selection, we have no alternative but to assume 
 that the variation is genetic in character. Body-size in birds and 
 mammals shows well the simultaneous yet distinct action of genetic 
 and non-genetic agencies. The amount and quality of the food 
 supplied to an animal limits its size, yet if food is supplied in abun- 
 dance and of proper quality, some races of animals attain greater 
 size than others. This is the result of genetic differences. 
 
 The analysis of such genetic differences is difficult. A pioneer 
 attempt was made by Galton (1889) in his study of human stature, 
 the inheritance of which he characterized as blending. This term 
 was adopted by Castle et al. (1909) in describing the inheritance 
 of ear-length and body-size in rabbits. A Mendelian interpretation 
 of size-inheritance was later advocated by Lang (1910), based on 
 the multiple-factor hypothesis of Nilsson-Ehle and this has now 
 received general acceptance. Davenport (1917) has recently applied 
 it to human stature, but has gone a step farther in assuming that 
 the genetic factors which govern size in one part of the body are 
 often not the same as those which govern the size of other parts. 
 
 Punnett and Bailey (1914, 1918) in their studies of size-inheritance 
 in poultry and in rabbits bring forward a different hypothesis.
 
 4 -KTIC STUDIES OF RABBITS AND RATS. 
 
 They attempt to explain the results of size-crosses with the aid of 
 genetic factors affecting the size of all parts, but relatively few in 
 number, a different potential effect on size being assigned to each of 
 the assumed factors. 
 
 With a view to throwing further light, if possible, on this confused 
 situation, a renewed investigation of size-inheritance in rabbits 
 was undertaken by me in January, 1917. To clarify the matter, it 
 seemed desirable to obtain races as pure as possible and as unlike as 
 possible in size, to breed each separately and study its variability 
 and at the same time and under similar conditions to cross the same 
 races and study the variability of the FI and F 2 generations of off- 
 spring. For this purpose two small races of rabbits were selected, 
 Polish and Himalayan, and one large race, that of the Flemish Giant. 
 Stock was obtained from exhibitors at the last previous Boston show 
 who had been awarded prizes for the excellence of their animals in 
 these several breeds. 
 
 In carrying out the original plan to study size-variation in the 
 uncrossed races, I have been only partiallysuccessful, but a good 
 series of cross-breds has been secured and studied. In the pure 
 races (plate 1) the number of adult individuals studied was, Polish 
 23, Himalayan 8, Flemish 5. Adult cross-breds have been produced 
 as follows: Polish X Flemish, F, 27, F 2 137; Polish X Himalayan, 
 F, 25, F, 55; Himalayan X Flemish, F! 17, F 2 70. The total number of 
 adult individuals studied for size-characters in this investigation is 
 367. The characters studied are weight, ear-length, and the fol- 
 lowing bone measurements: (1) skull length, (2) skull width anterior 
 to orbit, (3) skull width posterior to orbit, (4) length of femur, (5) 
 length of tibia, (6) length of humerus. 
 
 Weights were taken at intervals of about two weeks, from the 
 time of weaning to the attainment of full growth. As animals are 
 apt to increase in weight through the accumulation of fat after the 
 cessation of general growth, the adult weight of an animal is taken 
 as the maximum weight attained under one year of age. Small 
 races of rabbits attain maturity earlier than large ones. For example, 
 Polish rabbits are usually full-grown at ten months of age, whereas 
 Flemish may grow slowly after they are one year old. The skeletal 
 measurements studied are based for the most part on animals which 
 had attained the age of fourteen months, but some measurements 
 have been used of younger animals, when it has been found by com- 
 parison of different measurements that full growth had probably 
 been attained. Adult ear-length is attained much earlier than full 
 body-size. Growth of ears is practically completed at twenty weeks 
 of age. Accordingly, it has been possible to use the ear- measurements 
 of animals which died before they attained full body-size, and so 
 the totals for ear-length studies are greater than those for weight
 
 GENETIC STUDIES OF RABBITS AND RATS. O 
 
 (which is supposed to be complete at one year) or for bone- 
 dimensions, which as a rule are based on specimens fourteen months 
 old. 
 
 GROWTH-CURVES BASED ON WEIGHT. 
 
 Most of the rabbits were born in the spring and summer months, 
 May to August inclusive, but some were born as late in the year as 
 November and a few in the early part of December. None was born 
 in the months January to March inclusive. The young were usually 
 weaned when one month old, at which time periodical weighing of 
 the animals was begun. It was considered very desirable to raise all 
 the individuals born, for fear that if small-sized individuals should 
 succumb in competition with their larger brothers and sisters, the 
 statistical conclusions might be vitiated thereby. To this end, free 
 use was made of foster-mothers. Young under a week old may 
 readily be transferred from the nest of one mother to that of another. 
 In only one case have I known a mother to refuse to care for foster- 
 children substituted for her own of like age. Of course, notwith- 
 standing all our precautions, many young rabbits died before reaching 
 maturity, either from intestinal troubles in hot weather or from 
 nasal troubles ("snuffles") in cold weather. But a careful study of 
 our records indicates that there was no differential selection in favor 
 either of large or of small rabbits in these deaths. The young rabbits 
 were supplied with an abundance of suitable food, in summer grass 
 and oats, in winter hay, oats, and cabbage or carrots. Occasionally 
 a rabbit was not weaned promptly at one month of age. If, for 
 example, an individual seemed feebler than its fellows at weaning- 
 time, it might be left with the mother a week or two longer. Again, 
 differences in size were often observed at weaning-time between 
 litters of like ancestry, but of unlike number in individuals. If a 
 doe nurses six young, they will average smaller at weaning than will 
 young of similar ancestry nursed by two mothers, each of which 
 divides her milk among three young. Fanciers believe that this 
 affects the ultimate size of the offspring. They think that the 
 largest rabbits are obtained by rearing only two or three young to a 
 litter and by allowing these to nurse the mother for six weeks or 
 two months. Our observations do not support this view, but indicate 
 that the ultimate size attained is influenced very little, if at all, 
 by the size of the young at weaning, provided they are in good health 
 and growing condition and are thereafter fed abundantly. 
 
 Figure 1 illustrates the matter well. Rabbits 2650 and 2834 were 
 half-brothers. They had the same pure Flemish father and their 
 mothers were of the same pure Polish stock. Rabbit 2650 was 
 weaned at 29 days of age and grew slowly until he was 71 days old, 
 when he weighed 600 grams. Rabbit 2834 was raised by a foster-
 
 a 
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 mother alone, receiving all her milk until he was weaned at 71 days 
 old, when he weighed 1,530 grams, more than 2.5 times as much as 
 his half-brother at the same age. Notwithstanding this handicap 
 in his favor, he was overtaken in size by his early- weaned half- 
 brother at age 194 days, and was surpassed by him in adult weight 
 by about 150 grams. The bone dimensions of the two rabbits were 
 very similar, with a slight but probably not significant superiority 
 in favor of the late-weaned individual. In the case of neither rabbit 
 does the growth-curve show any interruption of healthy growth. 
 The form of the growth-curve is affected by the superior nutrition of 
 2834 during his first 2 months, but the ultimate size attained is not 
 influenced thereby. 
 
 Figure 1 also shows the growth-curve of a third rabbit (2578), 
 half-brother to each of the others (2650 and 2834). He was born 
 
 160 210 340 270 
 AGE. IN DAYS 
 
 Fio. 1. Growth-curves in weight of three F t rabbits which were half-brothers, all having the 
 same pure Flemish sire but each having a different pure Polish mother. Male 2578 
 wms born July 26, 1917; male 2660 was born August 9, 1917; male 2834 was born Decem- 
 ber 7, 1917. Note that the rabbit which was largest as an adult (2650) was smallest 
 up to 160 days of age, whereas the rabbit (2834) which was much the heaviest as a 
 young rabbit because he received all the milk of a foster-mother up to weaning at 71 
 day. of age, nevertheless fell below 2650 in adult weight. 
 
 just two weeks earlier than 2650, was weaned at the same age (29 
 days), but was slightly heavier at weaning and held the lead up to 
 age 144 days, when he was practically full-grown. His ears were 
 then of maximum length, 10.4 centimeters. On the same day 
 [December 17) the younger rabbit (2650), although lighter in
 
 GENETIC STUDIES OF RABBITS AND RATS. 7 
 
 weight, had longer ears (10.9 centimeters), a fact which foreshadows 
 his greater adult size. He kept on growing after passing age 144 
 days and ultimately became much heavier. His bone-measurements 
 were also greater, except in one instance, femur-length, which was 
 practically the same. In the case of this pair of half-brothers, the 
 environmental conditions were substantially identical. They were 
 born within a fortnight of each other, weaned at the same age, 
 and grew up under the same seasonal conditions on similar food, yet 
 they diverged in adult weight, bone-measurements, and ear-length 
 more than the pair (2650 and 2834) which had such different environ- 
 mental conditions. 
 
 From facts such as these, it is believed that accidental differences 
 in environment (though we have striven to avoid them) have little 
 to do with the size-differences observed among our rabbits. On the 
 other hand, it is clear that our purest races of rabbits are not perfectly 
 homogeneous genetically as regards size, since with the most carefully 
 controlled environment size-differences occur. 
 
 Figure 2 shows the growth-curves of two female rabbits, 3099 and 
 3100, litter mates borne by the same pure Himalayan mother to the 
 
 20 
 
 ts 
 
 1 
 
 S-o 
 
 2 
 t-" 
 
 is 
 
 
 
 
 
 
 
 - 
 
 
 
 
 T- 
 
 99 
 
 J 1 .. 
 
 100 
 
 
 
 
 T 
 
 ^ 
 
 ^ 
 
 ; 
 
 
 
 
 
 
 
 . 
 
 ft 
 
 #' 
 
 i 
 
 
 
 
 
 
 
 
 - 
 
 r 
 
 > 
 
 
 
 
 
 
 
 
 
 
 FIG. 2. Growth-curves of two 
 FI rabbits, litter-mates borne 
 by the same pure Himalayan 
 mother to the same pure 
 Polish sire, and kept together 
 in the same pen throughout 
 their growing-period. Note 
 difference in character of the 
 growth-curves. The rabbit 
 which was larger at weaning, 
 matures earlier and remains 
 smaller as an adult. 
 
 10 20 Z70 300 
 
 same pure Polish sire. Both were weaned on the same day at the 
 age 28 days. They were kept together in the same pen during 
 subsequent growth. At birth, 3099 was the larger of the two sisters 
 and maintained her superiority for about four months, when her 
 growth-rate began to slow up, while that of her sister, 3100, kept on 
 steadily. At about the age 170 days the originally smaller rabbit 
 surpassed her sister in size and held this relative position thereafter. 
 In every bone measurement she was a little larger than her sister, 
 but in ear-length they differed little, the smaller rabbit being credited 
 with having slightly longer ears. 
 
 From the weight-records made for each rabbit it is possible to 
 construct a growth-curve, as in the cases just discussed. Such 
 curves have been plotted for each pure-bred and each FI cross-bred
 
 s 
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 rabbit raised. From these curves, readings have been taken giving 
 the approximate weight of the individual at the ages of 30, 40, 60 
 days, and so on, at 30-day intervals, to the age 360 days. Combining 
 the weight records for each group of individuals, an average growth- 
 curve is obtained for the group, as shown in figure 3. 
 
 In this figure it is indicated that Polish rabbits are small at 30 
 days of age, but grow with fair rapidity until about 180 days old. 
 Then the growth-rate declines and growth is practically ended at the 
 age 210 days. In many cases the weight actually decreases again 
 after attaining a maximum at sexual maturity, or shortly thereafter, 
 as Punnett (1918) has observed. But such decline is not invariable, 
 and it may result from a variety of causes, such as less nutritious 
 
 FIQ. 3. Growth-curves of the 
 three races of rabbits, Polish, 
 Himalayan, and Flemish, 
 and of the groups of FI hy- 
 brids obtained by crossing 
 the three pure races. The 
 average adult weight of each 
 group of Fj hybrids is shown 
 for comparison with FI, be- 
 low which it falls in every 
 case. 
 
 AGE. IN 
 
 A ft, IN UAY9 
 
 food, a cold, or lactation (in females) . When normal conditions are 
 restored, the weight usually rises again and subsequent accumulations 
 of fat usually carry the final weight above the puberty maximum. 
 In plotting the growth-curves the maximum weight attained in the 
 first year is considered as persisting thereafter. This will account 
 for the fact that the plotted average curves do not show any decline, 
 even though the weight-curves of individuals would in many cases 
 do so. The rabbits that show increases in weight, due largely to 
 fattening subsequent to puberty (180 to 210 days), will explain the 
 fact that the weight-curve continues to rise until the end of the period 
 plotted, 360 days. 
 
 In the case of Himalayan and Flemish rabbits, the weight at the 
 age 30 days is greater than that of Polish rabbits. The growth-rate 
 
 uso greater, so that the growth-curves continue to diverge more 
 and more, one from another. The slowing up of growth at puberty
 
 GENETIC STUDIES OF RABBITS AND RATS. 9 
 
 (180 to 210 days) is also less abrupt and the increase in weight sub- 
 sequent to puberty is greater. The average weight at 360 days of 
 Polish rabbits of both sexes is less than 1,400 grams, for Himalayan 
 rabbits it is 1,800 grams, and for Flemish it is over 3,200 grams. 
 
 In Polish rabbits, as compared with other and larger breeds, the 
 initial weight is less, the growth-rate less, and the completion of 
 growth comes earlier. All these phases of growth combine to make 
 the ultimate weight smaller. Comparison of the growth-curves of 
 Polish and Flemish brings this point out very clearly. The Flemish 
 curve is far above the Polish curve at the outset and diverges from it 
 increasingly up to the age 360 days. The Himalayan growth curve 
 lies everywhere between the Polish and Flemish curves, but is much 
 nearer to the Polish. In form, however, it is more like the Flemish 
 curve, in that growth continues longer after puberty. 
 
 FI rabbits produced by crossing Polish with Himalayan have a 
 greater initial weight than either pure parent race and grow faster. 
 At puberty (180 to 210 days) the FI rabbits surpass Polish by over 
 500 grams. They are more than 40 per cent heavier. As compared 
 with Himalayans of like age, they are more than 20 per cent heavier. 
 At age 360 days, the FI rabbits are 45 per cent heavier than Polish, 
 but only 9 per cent heavier than Himalayan, since the slower-growing 
 Himalayans have lessened the superiority which the FI rabbits showed 
 at puberty, but have not extinguished it. 
 
 F 2 rabbits from this cross, obtained by mating the FI rabbits, 
 brother with sister or half-sister, show an average adult weight of 
 1,632 grams, which is intermediate between the adult weight of 
 Polish and Himalayan rabbits, the races originally crossed, being 
 20 per cent heavier than Polish and 10 per cent lighter than Hima- 
 layan. The superiority in size of the FI animals is a purely FI 
 phenomenon, as we shall see. It never persists into the F 2 generation. 
 Its existence is nevertheless an important practical consideration, 
 which makes grading and the crossing of breeds highly advantageous 
 under certain circumstances. 
 
 In the cross of Polish with Flemish rabbits, FI is in size well above 
 the intermediate between the parent races, another illustration of 
 FI vigor, although in this case FI does not surpass the larger race in 
 size. The form of the growth-curve is also intermediate. Maturity 
 is attained early, as in the Polish race, but the practical cessation of 
 growth comes later than in the Polish race, at 240 days rather than 
 at 200. The adult weight of the FI rabbits, at the age 360 days, 
 averaged 2,539 grams, as compared with 3,240 for Flemish and 
 1,359 for Polish. The intermediate would be 2,300 grams, which 
 the FI group surpasses by more than 10 per cent. In the Himalayan- 
 Polish cross, FI surpassed the intermediate by over 20 per cent, and 
 F 8 surpassed it by 3 per cent.
 
 10 GENETIC STUDIES OF RABBITS AND RATS. 
 
 In the Flemish-Polish cross, as in the Himalayan-Polish cross, 
 F falls below F, in size. It is found to be 2,128 grams as compared 
 with 2,539 for Fi. It is even less than the intermediate, 2,300 grams, 
 by about 8 per cent. 
 
 In the Flemish-Himalayan cross, the growth-curve for F! is very 
 similar in form to the curve for pure Flemish. There is a gradual 
 falling in the growth-rate at about 210 days, which indicates the 
 usual slowing-up influence of puberty, coming about a month later 
 than in Polish rabbits. But growth continues even after this retard- 
 ing influence sets in, just as it does in Flemish rabbits. The weight 
 at 360 days is 2,781 grams as compared with a strict intermediate 
 between the parent races of 2,523 grams, which it surpasses by 10 
 per cent, about the same relation found in the Polish-Flemish cross. 
 Again F shows a falling off as compared with FI to 2,466 grams, 
 which is 2 per cent less than the intermediate. 
 
 To summarize the foregoing observations: 
 
 (1) In races of small-sized rabbits the initial weight is small, the 
 growth-rate is low, and growth terminates early. Conversely, 
 rabbits of large-sized races have a large initial weight and growth 
 energy, which not only makes them grow faster, but also makes 
 them grow a longer time than do rabbits of small-sized races. 
 
 (2) When races of small rabbits are crossed with a race of large 
 rabbits, the initial weight, growth energy, and duration of growth 
 are all intermediate in character, but are greater than the strict 
 intermediate in the Fi generation and approximate it or fall slightly 
 below it in Fj. 
 
 (3) When two races of rabbits (such as Polish and Himalayan) are 
 crossed, which do not differ greatly in size, FI may surpass either 
 parental race in vigor of growth, though not in duration of growth. 
 Consequently the maximum advantage in size of FI over the parent 
 races will be attained at puberty. F will approximate the interme- 
 diate in size between the parent races originally crossed. 
 
 WEIGHT AND SEX. 
 
 In the foregoing pages the average weight of groups of individuals 
 has been under discussion without reference to individual variation 
 within each group or the effect of crossing on such variation, or the 
 relation of weight to sex. In any discussion of the inheritance of 
 weight, these questions must be taken into consideration. First 
 let us consider the relation of weight to sex. The "standards" of 
 the various breeds of rabbits formulated by breeders in England and 
 the United States make no specification as to the relative sizes of 
 the two sexes in the small breeds of rabbits, but in the large breeds 
 they regularly specify a larger size for females than for males. Thus, 
 the English standard for the variety Steel Gray Flemish Giant
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 11 
 
 (plate 1, F) specifies " Bucks shall be not less than 11 pounds and 
 does not less than 13 pounds." An American publication gives the 
 standard weight for Japanese rabbits as "bucks 7 pounds, does 8 
 pounds," that of French Silvers as "bucks, 9 pounds; does, 10 pounds 
 or over." 
 
 The existence of such specifications in breed standards implies 
 that, at least in large races of rabbits, the female either is naturally 
 larger than the male of like genetic constitution, except as to sex, or 
 else that the breeders have some expectation of making it so. 
 
 The relative weight of the two sexes in the groups of rabbits which 
 I have studied is shown in table 2. In the Polish breed, males were 
 found to be slightly heavier than females. The single male Himalayan 
 studied differed very little from the average of the 5 females; but in 
 the cross-bred rabbits of all three combinations, viz, Polish-Hima- 
 layan, Polish-Flemish, and Himalayan-Flemish, females were heavier 
 by from 50 to 200 grams (2.5 to 7.5 per cent) than were males derived 
 from the same cross. It seems clear, therefore, that the breed stan- 
 dards are correct in recognizing the greater weight of females than 
 of males, at least in the heavier breeds of rabbits. The difference is a 
 natural one, not arbitrary, but the amount of the difference has 
 probably been exaggerated in the standards, which call for a difference 
 of about 15 per cent. This is double the greatest difference observed 
 by me. 
 
 INHERITANCE OF WEIGHT. 
 
 Individual variation in weight can 
 methods. Maximal first-year weight 
 the few cases of rabbits received as 
 adults. For the present, the slight 
 difference in size of the two sexes 
 will be disregarded. The general 
 character of the variation in weight 
 is presented graphically in figures 4 
 to 6. The data on which these graphs 
 are based will be found in table 3. 
 
 Figure 4 shows that the modal 
 weight of Polish rabbits is about 
 1,400 grams, while Himalayan rab- 
 bits are about 400 or 500 grams 
 heavier. The Fi cross-breds are 
 heavier than either pure race, as 
 shown also in the growth-curves (fig. 
 3) . They vary symmetrically around 
 the class whose center is 1,949 grams, 
 designated class 19 in figure 4. The 
 Fj generation, which contained just 
 
 best be studied by statistical 
 will be dealt with, except in 
 
 NO. 
 
 F^.PXH 
 
 F..PXH 
 
 H 
 
 nri P^3 
 
 10 II 12 13 UVI5 16 17 18 I9ZOZI ZZ 23 24 
 WEIGHT, IN HEKTOGRAMS 
 
 Fia. 4. Polygons showing variation in 
 weight of pure Polish (P) and pure 
 Himalayan (H) rabbits, and of their 
 Fi and F t hybrid offspring. 
 
 twice as many individuals as
 
 12 
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 Fi, varies about class 16 as a mode, being about 300 grams lighter 
 in average weight than the Fi groups. The variability of this group 
 as measured by the standard deviation is only slightly greater than 
 that of FI, being 233 grams as compared with 218 grams for Fi. 
 
 20- 
 
 14- 
 
 rt- 
 
 F,,PXF 
 
 ..EL 
 
 1 12 13 * IS 16 n 18 19 ffl 21 ZL Z3 24 Z526 Zl X 23 3031 3233 34353637 3839 4041 
 WEIGHT, IN HEKTOGRAMS 
 
 Fio. 5. Polygons showing variation in weight of pure Polish (P) 
 and pure Flemish (F) rabbits, and of their FI and F 2 
 hybrid offspring. 
 
 Figure 5 shows the effect upon weight of the widest of the three 
 crosses, that between Polish and Flemish. The parental groups 
 are separated by over twenty classes. F! lies midway between them, 
 its mean falling in class 25. The variation polygon is rather flat 
 and wide, which would seem to indicate lack of complete genetic 
 
 uniformity in one or both parent races. 
 FI is of similar form, but is shifted about 
 four classes farther to the left. A sim- 
 ilar movement of the mean occurred in 
 the Polish-Himalayan cross between the 
 FI and the F 2 genera- 
 
 - tions. The variability, as 
 
 J^jn^ r measured by the stand- 
 
 _ c Mm _ ar d deviation, has in- 
 creased by about 25 per 
 cent, from 198 grams in 
 to 257 grams in F 2 . 
 
 WEIGHT, IN HEKTOGRAMS 
 
 Fio. 6. Polygons showing variation in weight of pure 
 Himalayan (If) and pure Flemish (F) rabbits, 
 and of their F, and F, hybrid offspring. 
 
 Figure 6 shows for 
 the Himalayan-Flemish 
 cross the variability in 
 
 weight of F! and F,. F! is strictly intermediate between the 
 parental races. Its mode lies in class 27, but the average is somewhat 
 higher, being 2,827 grams (table 3). The mode of F, lies three classes
 
 GENETIC STUDIES OF RABBITS AND RATS. 13 
 
 lower in class 24, the mean being 2,472 or about three and a half 
 classes lower than FI. The variability of F 2 is about 40 per cent 
 greater than that of Fi, being 230 grams instead of 162. 
 
 In neither of the Flemish crosses does the F 2 variation extend up- 
 ward into the range of pure Flemish, but is separated from it by from 
 four to seven vacant classes. In other words, the larger parental 
 type is not recovered in F 2 , doubtless because the number of inde- 
 pendent genetic factors involved is too great. If the larger parental 
 type is not recovered, it is not to be expected that the smaller type 
 would be recovered, since this would involve a chance recombination 
 of factors equally improbable of realization in a limited number of 
 offspring; but in reality the F 2 range does in every case extend down- 
 ward into the range of the smaller parent type; therefore either the 
 smaller type is more readily recovered, or what appears to be the 
 smaller type recovered in F 2 is really not such, but is a new genetic 
 combination or combinations which resemble in gross weight the 
 original parental type. The latter alternative seems more probable. 
 This view is supported by the observations on ear-length, which 
 character is closely correlated with weight, and yet in regard to 
 which neither the small. nor the large parental type is recovered in 
 F 2 , all F 2 variates occurring in the intermediate region. 
 
 EAR-LENGTH. 
 
 Ear-length is a character easier to study than body-weight, because 
 the adult condition is attained earlier and the races studied are more 
 sharply distinguished as to ear-length than as to weight. The ears, 
 as a rule, have attained their full growth at the age 150 days, or even 
 earlier in the case of the Polish race, whereas the weight continues 
 to increase slowly after that age. 
 
 The ear-length was recorded at the same time that the rabbits 
 were weighed, though less frequently, as little change was noted in 
 the ear-length after the age 150 days. After a rabbit had attained 
 that age his ears were measured merely often enough to make sure 
 that no further change had occurred and that the earlier measure- 
 ments had been accurate. A variation of 1 or 2 millimeters was 
 frequently noted in the measurements, and the final rating of each 
 rabbit was accordingly based on the approximate mean of the 
 recorded measurements. The measurement taken was read from a 
 ruler placed between the base of the right ear and the head, the ear 
 being then held vertically against the ruler and slightly stretched 
 and the reading made at the ear-tip. Small races of rabbits have 
 short ears; large races have both longer ears and longer skulls, as we 
 shall see. 
 
 The variation in ear-length of the groups of rabbits studied is 
 shown graphically in figure 7. The Polish rabbits studied range
 
 14 
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 in ear-length from 81 to 88 millimeters, Himalayan from 92 to 97 
 millimeters or about 1 centimeter longer-eared than Polish, while 
 the three Flemish individuals used as parents, notwithstanding their 
 diversities in weight, are remarkably uniform in ear-length, ranging 
 from 143 to 147 millimeters, or about 6 centimeters greater than 
 Polish and 5 centimeters greater than Himalayan. The three races 
 are very distinct and each by itself very uniform. 
 
 The data on the ear-length of the cross-bred rabbits is summarized 
 in table 4 and is shown graphically in figure 7. 
 
 CAR LENGTH, IN CENTIMETERS 
 
 Fio. 7. Polygons showing variation in ear-length of the three pure races of rabbits and of their 
 Fi and Fj hybrid offspring. 
 
 In the cross between the Polish and Himalayan breeds, which 
 differ in ear-length by about 10 millimeters, long ear appears to be 
 completely dominant. Variation is about the mode of the Himalayan 
 race and the average is practically the same (94.8 in the Himalayan, 
 94.9 in the FI group). But in F, the variation is much greater and 
 the range extends downward so as to include the mode of the Polish 
 race as well as upward to cover the entire range of the Himalayan 
 race and of FI. 
 
 The cross of Himalayan with Flemish gives results which are easier 
 to interpret. These two races considered singly are very uniform in 
 ear-length. Each varies closely about a mode widely separated 
 from that of the other race (see fig. 7). F! is about 4 or 5 millimeters 
 below the intermediate and varies little. F 2 has the same relation 
 to the intermediate, with practically the same mean, but is much 
 more variable, the standard deviation (table 4) having risen from 
 
 )8 millimeters in F, to 5.85 millimeters in F 2 , and the range from 8 
 millimeters to 24 millimeters. Nevertheless, the range of F 2 does not
 
 GENETIC STUDIES OF RABBITS AND RATS. 15 
 
 extend into the range of either parental race. A gap of 8 millimeters 
 separates the shortest-eared F 2 from the longest-eared Himalayan 
 rabbit, and a gap of 13 millimeters separates the longest-eared F 2 from 
 the shortest-eared Flemish. Hence it is clear that neither parental 
 combination is recovered in the total of 70 F 2 individuals studied. 
 Clearly, many independent factors must differentiate the parent races 
 as regards ear-length. 
 
 The cross of Polish with Flemish is a still wider one than that 
 just described and Fi is somewhat less uniform. It is, indeed, about 
 as variable as the F 2 obtained from the Himalayan-Flemish cross, 
 which fact indicates a greater genetic variability in the Polish than 
 in the Himalayan race as regards ear-length. Again, in this cross 
 FI falls below the intermediate between the means of the parent 
 races by about 5 millimeters. F 2 shows greatly increased variability 
 as compared with FI. The range has risen from 14 to 30 millimeters, 
 and the standard deviation from 3.76 to 6.05 millimeters (see table 4). 
 Nevertheless, the range of F 2 does not extend into that of either 
 parental race. Four vacant classes separate it from the range of 
 pure Polish and 20 vacant classes separate it from the range of pure 
 Flemish. It accordingly approaches the smaller race more nearly 
 than the large one (as in weight), but neither parental condition 
 reappears in F 2 , although this consists of 131 individuals. Again we 
 are forced to conclude that . numerous independent genetic factors 
 affecting ear-length differentiate the parent races. 
 
 The question may be raised whether there is a difference between 
 the sexes as regards ear-length, as there appears to be in regard to 
 weight. Table 5 answers this question in the negative. The sexes 
 differ very little in ear-length and neither is consistently greater than 
 the other throughout the groups. 
 
 BONE MEASUREMENTS. 
 
 The length of the skull has been measured, in these studies, from 
 the notch in the ventral margin of the occipital foramen to the 
 anterior surface of the incisor teeth in a straight line, measurement 
 being made with a caliper rule and readings taken in tenths of milli- 
 meters. Differences in skull-length between the races of rabbits 
 studied are less in amount than those which distinguish these same 
 races as regards ear-length. But it is desirable to ascertain whether 
 skull-length differences are inherited in a similar way and whether 
 they are correlated with differences in ear-length and body-weight. 
 Hence the study of skull-length will have value, even though its 
 results are not as clear-cut as those derived from other studies. 
 
 Polish rabbits have a skull-length of from 63 to 69 millimeters. 
 Himalayan rabbits have somewhat longer skulls, ranging from 66
 
 16 GENETIC STUDIES OF RABBITS AND RATS. 
 
 to 72.5 millimeters. The skull-lengths of 5 Flemish rabbits studied 
 range from 82.5 to 88 millimeters (see table 6). 
 
 The cross between Polish and Himalayan rabbits produced off- 
 spring surpassing both parent races in skull-length, as in body- weight, 
 a manifestation, no doubt, of heterosis or cross-bred vigor. The 
 FI averaged 70.2 millimeters in skull-length, the larger parent race 
 averaging 68.9 millimeters, the intermediate between the parents 
 being 67.3 millimeters. The average skull-length of F 2 in this cross 
 was exactly equal to that of the larger parent. It would seem that 
 the pure Polish and Himalayan races may have been below their 
 genetic possibilities in skull-length, owing perhaps to inbreeding. 
 
 The Himalayan-Flemish cross (table 6, F,, H.XF.) produced F t 
 animals averaging a little larger than the intermediate between the 
 parent races, and F t animals averaging a little less. But the F 2 
 animals were more variable than the F! animals, their standard 
 deviation in skull-length being 2.85 millimeters as compared with 
 1.79 millimeters for FI. The Polish-Flemish cross produced an Fj 
 generation close to the intermediate between the parent races as 
 regards skull-length, but FI fell more than 2 millimeters below the 
 intermediate. Again Fj was more variable than FI, the standard 
 deviations being 3.15 and 1.18 respectively. 
 
 Tables 7 and 8 show the variation of the several groups of rabbits 
 in skull-width measurements taken anteriorly and posteriorly respec- 
 tively to the orbit. It appears that Polish rabbits, though weighing 
 less than Himalayan rabbits and having shorter skulls, nevertheless 
 have skulls slightly broader. The F! rabbits from the Polish-Hima- 
 layan cross have skulls broader than those of either parent (as well 
 as longer, see table 6), and this superiority is retained in part in the 
 FI generation. These statements apply both to the anterior and 
 to the posterior skull-width measurements. Although the Polish 
 rabbits have slightly broader skulls than the Himalayans, neverthe- 
 less they do not transmit as much skull-width in crosses with Flemish 
 as do the Himalayans, for in every case the skull-width of the Hima- 
 layan-Flemish cross-breds is slightly greater than that of the 
 Polish-Flemish cross-breds. The explanation probably is that the 
 Himalayans transmit greater general body-size (weight) in crosses 
 with Flemish than the Polish do. Skull-width is sufficiently involved 
 in the general increase of all bodily dimensions to more than offset 
 the specific tendency of Polish to transmit a broad skull; for in 
 skull-length (table 6), the Himalayan-Flemish cross-breds exceed 
 the Polish-Flemish cross-breds even more than in skull-width. 
 
 The amount of variability in skull-width, as indicated by the 
 standard deviation (tables 7 and 8), is too erratic to have any par- 
 ticular significance. F, is not uniformly more variable than F! in 
 these cases.
 
 GENETIC STUDIES OF RABBITS AND RATS. 17 
 
 In studying bone-measurements, the length of 3 leg-bones has been 
 investigated, that of the tibia, the femur, and the humerus (tables 9 
 to 11). The bones measured are from the right side of the body. 
 The results are very similar in all three cases. The Polish-Himalayan 
 cross is followed by such increase in vigor that the cross-breds of 
 both the F! and the F 2 generations surpass in bone-dimensions the 
 intermediate between the parent breeds, but the Flemish crosses 
 produce offspring which even in FI fall slightly below the interme- 
 diate between the parent breeds, and in F 2 fall below it still more. 
 In every case F 2 is more variable than FI. 
 
 CORRELATION. 
 
 The question may properly be raised whether the same genetic 
 factors affecting size operate in all parts of the body, or whether 
 there are special factors affecting the size of each part. The latter 
 view is favored by Davenport in his studies of human stature; the 
 former seemed to me to be indicated in the statistics of rabbit meas- 
 urements published by MacDowell (1914). Wright (1918), from a 
 statistical analysis of the same data, concludes that both general and 
 special factors are indicated. The present investigation should be 
 able to throw further light on the subject. If two parts or dimen- 
 sions of the body are influenced by the same genetic agencies, they 
 should vary in unison, as the genetic agencies are made to vary by 
 means of cross-breeding. If they are influenced by different genetic 
 agencies, they should vary independently of each other. For this 
 reason it is desirable to study the correlation existing between each 
 pair of size-characters studied. 
 
 The results of such a study are contained in the correlation tables 
 (tables 12 to 29). These show strong correlation in every case 
 between size of the body as a whole and size of each of its parts, as 
 well as between different parts of the body. Most of the correlation 
 coefficients (table 30) lie between 0.80 and 0.90, where 1.00 would 
 indicate complete identity of all agencies affecting size, whether 
 genetic or non-genetic. The highest correlations are found in com- 
 paring the lengths of the long bones of the legs, humerus with femur 
 (0.906) and with tibia (0.904), and femur with tibia (0.927). Next 
 in closeness of correlation comes the relation between skull-length 
 and the length of the leg-bones (0.806 to 0.871), but the correlations 
 of weight with bone-measurements are almost as close (0.820 to 
 0.852), except in the case of the tibia, where the coefficient falls to 
 0.758. There is a very similar range in the correlation coefficients 
 between ear-lengths and weight (0.836) and ear-length and the 
 various bone-measurements (0.823 to 0.836), except again in relation 
 to the femur, where occurs the lowest correlation of the entire 15 
 studied, viz, 0.741.
 
 18 GENETIC STUDIES OF RABBITS AND RATS. 
 
 In the case of MacDowelTs observations (Castle, 1914), correlation 
 coefficients were obtained somewhat lower than those here recorded, 
 but still notably high. The leg-bone correlation coefficients (the 
 highest of any in both sets of observations) were in MacDowell's 
 rabbits 0.858, 0.857, and 0.791, where the present observations give 
 0.927, 0.906, and 0.904. The skull-length correlation with tibia 
 was, in the former case, 0.701, in the latter 0.806. In general, the 
 correlations run about 10 per cent higher in the present set of obser- 
 vations, which is probably due to the greater range of variation in 
 size in the lot of rabbits OP which these observations have been made. 
 The number of rabbits studied in the two cases is comparable, a 
 maximum of 376 in the case of MacDowell's rabbits, of 348 in the 
 present case. But the range of size-differences is greater in the 
 present case. For example, the tibia classes in MacDowell's rabbits 
 range from 88 to 110 millimeters; the range in the present lot is from 
 80 to 112 millimeters. The correlation is strongest where the range 
 is most extended, for at the ends of the range, where only individuals 
 of pure race occur, genetic differences are greatest and non-genetic 
 agencies sirk into insignificance, whereas at the middle of the range 
 Don-genetic agencies exert a relatively greater influence. 
 
 That this is so can be shown by a fuller analysis of one of the 
 correlation tables. Let us take, for example, the correlation between 
 femur and humerus (table 24). The correlation coefficient (r) for 
 all the rabbits (343) taken collectively is 0.906. For the pure races 
 only (table 25) it is 0.980, almost perfect correlation, indicating nothing 
 but genetic agencies at work. For the Fj cross-breds (table 26), 
 which should be no more variable than the more variable of the 
 parent races, r is 0.888, much lower than for the pure races, because 
 now only intermediate forms are present, the extremes represented 
 by the pure parent races not being present. For F 2 by itself (table 
 27), r is 0.878, very nearly the same as for Fi, it will be observed, 
 although the genetic diversity is greater. For F 2 is more variable 
 than F! as regards both femur and humerus, yet the correlation indi- 
 cated is practically the same, the difference being no greater than the 
 probable error. If there were independent inheritance of factors 
 affecting the size of femur and of humerus respectively, the correla- 
 tion should be less close in F a than in FI because of recombination of 
 independent genetic factors, but such is not the case. Hence we 
 are forced to conclude that exactly the same genetic agencies affect 
 the size of femur and humerus. Similar reasoning would lead to 
 the conclusion that the same is true of all size features studied, in- 
 cluding not only bone-dimensions, but also weight and ear-length.
 
 GENETIC STUDIES OF RABBITS AND RATS. 19 
 
 GENERAL OR LOCAL SIZE FACTORS. 
 
 In the light of these facts, what should be our attitude toward the 
 view (expressed by some students of human heredity) that mixed 
 races are likely to contain individuals with physical maladjustments 
 and disharmonies? On this view it is assumed that there are inde- 
 pendent genetic determiners affecting the size of the different parts 
 of the body. If so, when races of different size are crossed, recom- 
 bination of genetic factors will in later generations produce some 
 parts larger, others smaller, than the general average of the races 
 crossed. This will result in disharmonic combinations, as, for 
 example, hearts too large or alimentary tracts too short for the bodies 
 in which they are found. Is there any real ground for such appre- 
 hension? I think not. There is in health a perfect correlation in 
 size of each part with every other part of the same body and with 
 the size of the body as a whole. The modern sciences of embryology 
 and physiology tell us why this is so. It is (1) because development 
 of the individual from the fertilized egg is so largely epigenetic, each 
 stage growing out of its immediate predecessor; and (2) because it is 
 so largely controlled by internal secretions. 
 
 The view of the genetic independence in size of the various parts 
 of the body is a sporadic relapse into preformationism, such as was 
 perhaps excusable to the Grecian mind when, without the control of 
 observational or experimental science, it fancied animals to arise by 
 chance coming together of arms, legs, and other parts which originally 
 floated free and unconnected in primordial slime. The day for such 
 preposterous ideas is past. There may be valid reasons why mixing 
 of the more distinct human races should not be advocated, reasons 
 perhaps sociological, but there need be no fear that an animal or- 
 ganism will result whose parts are not properly coordinated. We 
 are only beginning to understand the mechanism of such coordination, 
 through studies of the ductless glands, but it is already clear that 
 such coordination and control are very complete and are adequate 
 for the production of harmonic organisms in the widest racial crossing 
 possible in the animal kingdom. 
 
 I think that a strong probability has been established that the 
 genetic factors which affect size in mammals are general in their action, 
 exclusively so. In this last particular I dissent from the view ex- 
 pressed by Wright (1918) who, from a statistical examination of 
 MacDowell's data, concluded that the genetic factors indicated 
 were in minor part special and local in action. Davenport has advo- 
 cated a similar view concerning the inheritance of human stature, 
 but on grounds which appear to me to be inadequate for two reasons: 
 first, because of the imperfect character of his data, and secondly 
 because of unwarranted deductions from them. Measurements of 
 the several elements of human stature made on the living subject
 
 20 GENETIC STUDIES OF RABBITS AND RATS. 
 
 are far from being precise and consequently correlations between 
 these measurements are unreliable. Yet such is Davenport's entire 
 material. He resolves the total stature (standing height) into four 
 elements, only two of which are capable of direct measurement, viz, 
 the "fibula" and the "torso." The first element of the total stature 
 is the "fibula," which is the "height of fibula head (attachment of 
 external lateral ligament) from the floor." The second element, 
 the "femur," is obtained by subtracting from the standing height, 
 first the "fibula," and then the "sitting height." The third element, 
 the "torso," is obtained by a measurement from chair-bottom to 
 upper end of sternum, and is likely to be vitiated (as is the sitting- 
 height) by amount of flesh or fat or clothing on buttocks. The 
 fourth element, the "head and neck," is arrived at by subtracting 
 "torso" from "sitting height." There are altogether too many 
 chances of error or inaccuracy in these measurements to make them 
 comparable in reliability with measurements made on the actual 
 skeletal elements of individuals. 
 
 Davenport argues for the independent inheritance of the four 
 elements of stature on the ground that races and families have 
 characteristically different proportions of the total stature formed 
 by each of its elements. In support of this view he figures (from 
 "Martin, 1914") side by side photographs of a "Dinka negro" and a 
 "Chiriguan Indian." The enlargement of these pictures is arranged 
 so as to make the individuals of seemingly the same total height, 
 whereby their difference in proportions is obvious. The limbs of the 
 negro are seen to be relatively long, those of the Indian relatively 
 short. If, now, each is a fair representative of his race, we must 
 conclude that Dinka negroes inherit as a racial character limbs 
 relatively long, while Chiriguan Indians inherit as a racial character 
 limbs relatively short. But a comparison of the pictures shows also 
 that the Indian stands much nearer the observer than the negro, 
 as the size of his head, eyes, hands, and feet and the diameter of leg 
 and arm are much greater. It is his nearness to the observer that 
 makes him appear as tall as the negro in the picture. He is accord- 
 ingly of absolutely short stature, whereas the negro is of absolutely 
 tall stature. The absolutely tall individual (and race) accordingly 
 has relatively long limbs, the absolutely short individual (and race) 
 has relatively short limbs. Is this association accidental? If not, we 
 may be dealing here with one racial difference, not two. 
 
 Tall stature and relatively long limbs may be due to one and the 
 same genetic cause, and not be independently inheritable. Daven- 
 port's own paper indicates that this is probably true. He repro- 
 duces another figure (fig. 8) from "Martin, 1914," in which it is 
 shown by diagrams that the proportions of the human body change 
 in the lifetime of the individual, the limbs becoming relatively longer
 
 GENETIC STUDIES OF RABBITS AND RATS. 21 
 
 as the absolute stature increases. There is the same difference in 
 proportions between boy and man as between Chiriguan Indian and 
 Dinka negro. The inheritance of boy and man is the same; one is a 
 further development of the other. 
 
 May it not be that tall and short human races are the result of 
 interruptions at different stages of the general growth process? If so, 
 races or families with " relatively long fibula" will be such simply 
 because they are tall races or families, and both the tallness and the 
 long fibula will be due to one and the same ontogenetic cause, long- 
 continued growth. It is no accident, probably, but the result of a 
 common genetic and ontogenetic agency, that South Italians are 
 (1) short of stature, (2) short-limbed, and (3) mature (cease to grow) 
 early, whereas Swedes and Scotch are (1) tall, (2) long-limbed, and 
 (3) mature late. There is a similar difference between the Polish 
 and Flemish breeds of rabbits. We have evidence of the most posi- 
 tive sort that a single genetic agency is responsible in one case for 
 (1) small size, (2) short ears, and (3) early maturity, and in the other 
 for (1) large size, (2) long ears, and (3) late maturity. In one case 
 we have initial energy of growth small (as evidenced by the form of 
 growth-curve) and soon spent; in the other case, growth energy is 
 strong and persistent. This single difference will account for all the 
 closely correlated size-differences, respectively, of the small and of the 
 large races of rabbits. 
 
 What is the nature of this genetic agency? Is it a gene, or an 
 assemblage of linked genes, or what is it? I do not think that we can 
 give a full and final answer to these questions at present, but we can 
 at least outline certain possibilities and exclude others. 
 
 First, inheritance of large or small size in rabbits is influenced 
 equally by the father and by the mother. No difference can be 
 detected between the results of reciprocal matings between large- 
 sized and small-sized races. This indicates that sperm no less than 
 egg is the vehicle of transmission and makes it probable that the 
 chromosomes are concerned in the transmission. If so, the agency 
 may properly be a gene or genes. 
 
 THE NUMBER OF SIZE GENES. 
 
 It is clear from the results of crosses between large-sized and small- 
 sized races of rabbits that more than one gene must be involved, 
 since there is no reappearance in F 2 of the grand-parental size-classes. 
 The question may be raised how many genes, supposing all to be of 
 like influence on size, will account for the observed F 2 distribution. 
 There are two ways in which one might attempt a statistical solution 
 of this question. He might consider how frequently the grand- 
 parental conditions (extremely large or extremely small) reappear in 
 F 2 and make this a basis for estimating the number of independent
 
 22 GENETIC STUDIES OF RABBITS AND RATS. 
 
 genetic factors involved. Thus, reappearance of the extremely 
 large type in 1 individual in 4 would indicate one genetic factor; its 
 reappearance once in 16 individuals would indicate two factors, and 
 so on; but in the present case the extremely large type has not reap- 
 peared at all in F,, so that this method is scarcely applicable. On 
 the multiple-factor theory, it may be that too small a number of F 2 
 individuals has been produced to make the reappearance of an extreme 
 type probable; but the form of the variation curve for F 2 would still 
 be available as an index of the number of factors involved, even if 
 this curve was not sufficiently extended to include the grand -parental 
 classes. With this idea in mind, I have suggested (Castle, 1921) a 
 comparison of the standard deviation of F 2 with the standard 
 deviation of Fi as a basis for estimating the number of independent 
 factors involved in cases of so-called blending inheritance. Dr. 
 Sewall Wright, who has kindly assisted in this matter, gives the fol- 
 lowing formula for computing the number (n) of independent factors 
 involved : 
 
 In this formula D is the difference between the means of the 
 parental (pure) races, a\ is the standard deviation of Fi, and <r 2 is 
 the standard deviation of F 2 . 
 
 In table 31 are shown the results obtained by applying this formula 
 to the six most important measurements studied in the case of each 
 of the three different racial crosses. For the Polish-Himalayan 
 cross, in which the parent races do not differ greatly in size, a differ- 
 ence of from one to three genetic factors is indicated by the different 
 measurements studied, the average being two factors. For the 
 Himalayan-Flemish cross the indicated number of factorial differences 
 ranges from 5 to 10, average 8.2. In both these crosses the results 
 are fairly consistent throughout the different measurements. But 
 this is not the case in the Polish-Flemish cross. Here the bone- 
 measurements give low values (between 5 and 6), evidently too low, 
 since they are less than those of the Himalayan-Flemish cross, in 
 which the parent races differ less. But the weight and ear-length 
 values are high, about double the values given by the Himalayan- 
 Flemish cross. The average for the series is 10.5, which is a value of 
 the proper magnitude in relation to the values given by the other 
 two series, since the number of factorial differences between Polish 
 and Flemish, one would suppose, should about equal the sum of the 
 differences (1) between Polish and Himalayan and (2) between 
 Himalayan and Flemish, because Himalayan stands in size between 
 the other two races. It is noteworthy that the results given by 
 weight and by ear-length respectively are in each cross very similar.
 
 GENETIC STUDIES OF RABBITS AND RATS. 23 
 
 The fact is appreciated that these are at best rough estimates, 
 since (1) it is improbable that all genetic factors affecting size have 
 individually the same amount of influence, and (2) it is improbable 
 that the FI generation is in each case devoid of genetic variability, 
 both of which assumptions are made in the formula employed. 
 Nevertheless, the results may have some value as indicating whether 
 many or few chromosomes are concerned in the inheritance of size in 
 these crosses, if we adopt the chromosome hypothesis. Any addi- 
 tional test which we can apply to that hypothesis will have cumula- 
 tive value. 
 
 The number of chromosomes in the rabbit, according to the sum- 
 mary of Miss Harvey (1920), is estimated by the most recent ob- 
 servers at 10 to 12, an earlier estimate being 14 to 18. It would 
 accordingly seem probable, on the chromosome hypothesis, that all 
 the chromosomes are concerned in size inheritance in such a wide cross 
 as that between Polish and Flemish Giant rabbits, while in the other 
 crosses part only of the chromosomes are concerned. 
 
 We should by this method not expect to find a number of factors 
 indicated greater than the total number of chromosomes, since even 
 if several or many genes in a single chromosome influenced size, 
 these would not appear in the general result as independent agencies, 
 but as a single agency consisting of a linked system. The result given 
 by this formula must accordingly be interpreted, not as indicating 
 the total number of genes affecting size, but as the probable number of 
 chromosomes (or linkage systems) containing such genes. 
 
 SIZE AND SEX. 
 
 The relation of size to sex in rabbits has already been discussed 
 briefly in connection with weight; we may now discuss this question 
 further, and in relation to bone-dimensions and ear-length as well 
 as weight. For this purpose, the groups of cross-bred rabbits afford 
 the best material, because their numbers are largest and they are 
 free from possible effects on size of different degrees of inbreeding. 
 The pertinent facts are brought together in table 32. It will be 
 observed that males are consistently larger in all bone measurements, 
 but females surpass in weight. Yet none of the differences is very 
 great. It is evident that the male is a bigger-framed animal than 
 the female (as in mammals generally), though the female puts on 
 more flesh. But the size-differences of the sexes are less than in most 
 mammals. In length of leg-bones the male exceeds the female by 
 percentages ranging from 0.5 to 1.5. In skull-length the difference 
 is very slight, 0.1 or 0.2 per cent. But in males the skull-width, 
 between the outer edges of the zygomatic arches, is greater by 2 or 
 2.5 per cent. Wright (1918), on the basis of MacDowell's observa- 
 tions, assumed that sex is a specific differential factor affecting the
 
 24 GENETIC STUDIES OF RABBITS AND RATS. 
 
 length of the hind-leg in rabbits, but it is evident from table 32 that 
 the action of this factor is general, not local, and that it affects the 
 general framework of the rabbit, not its leg-length alone or its hind-leg 
 rather than its front-leg. 
 
 In the size of the soft parts of the body as, for example, ear- 
 length and body-weight females in general surpass males. But it is 
 possible that this difference would not hold for certain small races of 
 rabbits. We have already noted that in our pure Polish rabbits the 
 average weight of the males was actually greater than that of females, 
 although in all the large races and in all our cross-breds, females are 
 heavier than males, the difference amounting to about 5 per cent. 
 In ear-length there is very little if any difference between the sexes. 
 Males have slightly longer ears among the Polish-Himalayan cross- 
 breds, but females among the Flemish cross-breds. The differences 
 are of doubtful statistical significance. 
 
 The differences in size due to sex are too small to affect materially 
 the correlation coefficients obtained by comparing bone-measure- 
 ments, ear-length, and weight, as in tables 12 to 30. Of this I con- 
 vinced myself by making separate correlation tables for the two 
 sexes in the case of weight correlated with length of tibia, in which 
 the disturbance due to sex would be at a maximum, since males and 
 females would in these two characters diverge most and in opposite 
 directions, males having a longer tibia, but females being heavier. 
 The correlation between weight and tibia based on both sexes is 
 0.7580.015 (table 20). For the males alone it is 0.7450.023; 
 for the females alone it is 0.775 0.021. The correlation is not in- 
 creased by tabulating the sexes separately. For the sexes combined 
 the correlation is practically the mean of the values obtained for the 
 sexes separately. Neither sex departs more than the probable error 
 from the combined value. 
 
 TESTS FOR LINKAGE WITH COLOR OR OTHER COAT 
 CHARACTERS. 
 
 Hoshino (1915) demonstrated the existence in garden peas of a 
 strong linkage in heredity between a quantitatively varying char- 
 acter, time of flowering, and red color of the flowers. It would be of 
 interest to know whether in animals a similar linkage exists between 
 large or small size and any particular color gene. I can not discover 
 that such is the case in rabbits, probably for the reason that size in 
 rabbits is determined by genes located in many or all chromosomes, 
 whereas each color gene is located in a single chromosome. In each 
 of the two crosses with Flemish, a different albino allelomorph was 
 introduced by the small-sized parent. Albinism was completely 
 recessive in F,, but reappeared in F t in approximately one-fourth of 
 the individuals. If any linkage existed between albinism and small
 
 GENETIC STUDIES OF RABBITS AND RATS. 25 
 
 size, a majority of the F 2 albinos should have been of small size, 
 averaging less in weight than their colored brothers and sisters. 
 Such was not the case. In the Polish-Flemish cross, 29 out of 113 
 F 2 individuals reared to maturity were albinos. The average adult 
 weight of the albinos was 2,155 grams, that of the entire F 2 population 
 was 2,128 grams. The albinos were actually a little larger than the 
 average, although they inherited their albinism from the small-sized 
 grandparent. Hence no linkage is indicated. In the Himalayan- 
 Flemish cross a similar result was obtained; 11 out of 62 adult F s 
 individuals were Himalayan albinos. They averaged in weight 2,535 
 grams, the average for the entire population (62) being 2,468 grams, 
 or slightly less. The small size of the Himalayan grandparent did 
 not make the Himalayan individuals any smaller (or even quite as 
 small) as their colored brothers and sisters. Hence no linkage is 
 indicated. 
 
 Yellow color and dilute pigmentation are two recessive unit- 
 characters which were transmitted by the Polish male used in the 
 Polish-Flemish crosses, but were not transmitted by the Flemish 
 animals used in those crosses. This fact affords an opportunity to 
 test the occurrence of linkage between small size and either yellow 
 or dilute pigmentation. 
 
 Three yellow F 2 males averaged in adult weight 2,133 grams. 
 The entire group of 28 F 2 males, of which the 3 yellows formed a part, 1 
 all having descended from the same pair of grandparents, averaged 
 2,156 grams, substantially the same amount. Hence there is no 
 indication of linkage between yellow and small size. 
 
 Fourteen F 2 dilute individuals derived from the mating just men- 
 tioned or from other reciprocal Polish-Flemish matings averaged in 
 weight 2,086 grams, while the average weight of the entire F 2 gener- 
 ation in this cross was 2,126 grams, which is only 40 grams heavier. 
 This difference again is too small to give any probable indication of 
 linkage between dilution and small size. 
 
 Another recessive coat-character, angora (long woolly hair), 
 appeared unexpectedly in the F 2 generation of a cross between a 
 Flemish female (7) and the Polish male (3). A further study of the 
 case showed that the angora character was transmitted by the 
 Flemish parent but not by the Polish. In this case, then, linkage, 
 if found at all, should be found between large size and angora coat; 
 10 adult angoras occurred among the 42 F 2 young reared from this 
 mating. The angoras averaged in weight 2,174 grams; the entire F s 
 group averaged 2,194 grams, or 20 grams heavier. Clearly, there- 
 fore, angora was not linked with large size. 
 
 1 The reader may wonder why the number of yellow grandchildren was so small. In reality a 
 fourth yellow individual was produced, a female, but she died before attaining adult size. 
 Further, the Polish grandparent transmitted yellow in only half his gametes, so that only part 
 of the Fi individuals inherited the character from him.
 
 _><; GENETIC STUDIES OF RABBITS AND RATS. 
 
 It can therefore be stated with confidence that no linkage is found 
 between large or small size and the four coat-characters, albinism, 
 dilution, yellow, and angora. A reason for this has already been 
 suggested, that each of the coat-characters is determined by a single 
 recessive gene borne probably in a single chromosome, and in the 
 case of each of the four characters in a different chromosome, whereas 
 size depends on many genes borne probably in many different chro- 
 mosomes or in all the chromosomes. 
 
 In table 33 is recorded the color of each rabbit studied, but 
 an examination of these records reveals nothing essentially new as 
 regards color inheritance. It does, however, serve to confirm the 
 discovery made by Punnett (1912) of a peculiar form of the extension 
 factor (E) which he observed in the offspring of a certain Himalayan 
 rabbit. To be sure, Punnett did not call it a peculiar form of the 
 extension factor, but rather a darkener (D) inseparably coupled with 
 the extension factor (E), so that the supposed couplet, darkened 
 extension (DE of Punnett), behaved as the allelomorph of ordinary 
 extension (E) and of yellow (e). A series of 3 allelomorphs was thus 
 established by Punnett's observations, and it would seem desirable 
 for simplicity so to designate them. I have elsewhere employed 
 the symbol E' for Punnett's darkened extension (DE). The order of 
 dominance of the 3 allelomorphs is E' (dark extension), E (ordinary 
 extension), e (restriction or yellow). 
 
 Our observations on the Flemish crosses reveal the probable 
 source of Punnett's peculiar darkened extension found in his Himala- 
 yan doe 7. No Himalayans of pure race, that we have had, possessed 
 the darkened extension, but it is regularly present in Flemish Giant 
 rabbits of the varieties steel gray and black. Doubtless Punnett's 
 Himalayan doe 7 was derived from a Flemish cross made with the 
 idea of intensifying or darkening the pigmented markings of the 
 Himalayan (nose, ears, tail, feet). 
 
 All our pure Flemish rabbits have possessed darkened extension. 
 The black doe, B, was apparently homozygous for this factor. She 
 transmitted it to two young, d"2473 and 9 2474, which she had by 
 the Polish male 3, whose formula was Ee. These two young are 
 recorded as black, but as full-grown adults it was noted that each of 
 them at times showed slight indications of ticking on the neck or 
 front legs, and among their offspring were typical steel grays (e. g., 
 93108, 93111, c?3420), similar in appearance to 97 (plate 1, F). 
 That animal was heterozygous for dark extension, her formula 
 being E'E. Mated with the Polish buck 3, she had a litter of 9 
 young, of which 5 were gray, 2 steel-gray, and 2 black. The 5 gray 
 never produced any steel-grays when mated inter se, which shows 
 that they did not inherit darkened extension, but only ordinary 
 extension, E. But the steel-gray and the black young produced
 
 GENETIC STUDIES OF RABBITS AND RATS. 27 
 
 steel-gray offspring in various matings, and this shows that they did 
 inherit darkened extension, E r , from their mother. Their sire, as 
 we have stated, did not transmit E f , but was of the formula Ee. 
 The steel-gray Flemish buck 2, used in crosses with both Polish and 
 Himalayan does, was also heterozygous for dark extension, his 
 formula being E'E. By Himalayan does (EE) he had 8 steel-gray 
 and 9 gray offspring (see table 33, VI). By Polish does (EE or Ee) 
 he had 10 steel-gray and 6 gray young (table 33, V). Unlike 97, 
 he had no black young. He was homozygous for the gray or agouti 
 factor (A) whereas 97 was probably heterozygous for this factor. 
 Hence the two black young of 9 7, her formula being E'EAa, but 
 that of 6*2 being E'EAA. 
 
 These results confirm the conclusions of Punnett and show that 
 
 (1) Any individual which is homozygous for darkened extension is 
 devoid of agouti ticking, whether or not the agouti factor is present. 
 Examples are found in black Flemish and black Siberian rabbits. 
 (2) Any individual which is heterozygous for dark extension (E'E or 
 E'e) will ordinarily be steel gray in color ("agouti-black," Punnett) 
 if the agouti factor is present, either heterozygous or homozygous, but 
 such individuals are often black (showing no trace of agouti ticking) 
 in their first coat, although they develop the ticking in later pelages. 
 
 However, some individuals of formula E'EAa may show little or 
 no ticking in their adult pelages, as, for example, the FI 9 2474 and 
 her brother 6" 2473, which produced steel-gray young as well as 
 black ones when mated with each other. If the allelomorph of E 
 present in a heterozygous individual is e rather than E } the steel-gray 
 is usually (perhaps always) clearly visible in the adult coat. Punnett 
 speaks of individuals of this sort as invariably " black," but his 
 classifications were apparently based exclusively on the juvenile coat. 
 
 In the F 2 generation of the Flemish-Polish cross, but not of the 
 Flemish-Himalayan cross, appeared dilute pigmented individuals 
 having dark extension. These I have called ' ' steel-blue "and" blue. ' ' 
 They correspond with the classes steel gray and black of the intense- 
 pigmented series. From the fact that no dilutes appeared in F s 
 from the Flemish-Himalayan cross, it is clear that dilution was 
 introduced in the Polish race, but not in either of the other races. 
 Similar reasoning shows that the color yellow (e) also was not present 
 in either the Flemish or the Himalayan individuals employed 
 in the crosses, but only in the Polish individuals; for yellow F 2 
 individuals appear in the Polish-Flemish cross, but not in the 
 Himalayan-Flemish cross. Finally, angora coat appears in F 2 of 
 the Polish-Flemish cross, but not in either of the other crosses. 
 Even in the Polish-Flemish cross angora appears only in the F 2 of a 
 single mating, that between Flemish 97 and Polish c?3. But c?3 
 was employed also in the Himalayan-Polish crosses, yet no angora
 
 1?S GENETIC STUDIES OF RABBITS AND RATS. 
 
 individuals appeared in those crosses. Therefore c?3 can not have 
 transmitted angora coat. Accordingly, Flemish 97 must have 
 done so. She was not employed in the Flemish-Himalayan cross, 
 otherwise we should have expected to see angora individuals in the 
 F, of that cross also. 
 
 SUMMARY. 
 
 1. Studies have been made of the weight, ear-length, and several 
 bone-dimensions of three races of rabbits, and of the first and second 
 generation hybrids between these races. 
 
 2. Two of the races (Polish and Himalayan) are of small size, like 
 the wild rabbit of Europe, the ancestral species. The third race 
 (Flemish Giant) is very large, a racially new condition. 
 
 3. Crosses between the pure races produce in general individuals 
 of intermediate size both in FI and F 2 , so that the inheritance is 
 correctly described as blending. But when the parent races do not 
 differ greatly in size (as, for example, the Polish and Himalayan races), 
 the size of FI individuals may be increased by heterosis beyond what it 
 would be through inheritance alone, so that the size of the larger pure 
 race is approximated or even surpassed. Nevertheless, with the 
 disappearance of the heterosis effect in F 2 the average size of the 
 cross-breds sinks to a strictly intermediate position. 
 
 4. The heterosis effect is seen in the FI generation produced by 
 crossing a large with a small race, no less than in the cross between 
 two small races, but when the difference in size between the races 
 crossed is large, the heterosis effect is not sufficient to obscure the 
 essentially blending or intermediate character of the inheritance in 
 FI. It merely produces a rise in the FI average size above the strictly 
 intermediate position, which F 2 in every cross closely approaches. 
 
 5. The variability in size of F 2 is regularly greater than that of FI, 
 which in accordance with the multiple-factor hypothesis is regarded 
 as indicating the occurrence of genetic factors affecting size in several 
 different chromosomes or linkage systems. 
 
 6. An attempt has been made by statistical methods to estimate 
 how many different chromosomes (or linkage systems) are concerned 
 in the inheritance of the size-differences found in the three race 
 crosses, with the following average results: for the Polish-Himalayan 
 cross, at least two chromosomes; for the Himalayan-Flemish cross, 
 about eight chromosomes; for the Polish-Flemish cross, ten or more 
 chromosomes. As the total number of chromosomes in the rabbit is 
 estimated at 10 to 12 pairs, it seems probable that all chromosomes 
 are concerned in size-inheritance. 
 
 7. A study has been made of the correlation between weight, ear- 
 length, and the several bone-dimensions studied, with a view to dis- 
 covering whether the same genetic agencies influence size in different
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 29 
 
 parts of the body, or whether factors, independent one of another, 
 govern size in different parts of the body. The conclusion is reached 
 that the genetic agencies affecting size in rabbits are general in their 
 action, influencing in the same general direction all parts of the body. 
 The same would probably be found true for man and other mammals, 
 perhaps for vertebrates in general, but not for plants in which hor- 
 mone action is less in evidence. 
 
 8. No linkage relation has been found to exist between size and 
 any simple (unifactorial) Mendelian character, such as albinism, 
 yellow coat-color, dilution, or angora coat. This result is in har- 
 mony with the view that unifactorial characters have their genes 
 located each in a single chromosome, while size is influenced by genes 
 located in many or all chromosomes. 
 
 9. In rabbits, size differences correlated with sex are very slight. 
 In skeletal dimensions the adult male averages larger by 1 or 2 per 
 cent, but in weight females surpass males, particularly in the larger 
 breeds of rabbits; yet the differences are so small as not to disturb 
 appreciably the correlation coefficients based on data in which both 
 sexes are included. In ear-length no significant difference between 
 the sexes can be detected. 
 
 TABLES. 
 
 TABLE 1. Average weight in grams of rabbits of the several groups studied, at various ages. 
 Data used in the construction of figure 8. 
 
 Group. 
 
 No. 
 
 Age in days. 
 
 30 
 
 308 
 
 605 
 363 
 377 
 350 
 
 40 
 
 414 
 422 
 870 
 459 
 478 
 521 
 
 60 
 
 549 
 574 
 1172 
 661 
 683 
 769 
 
 90 
 
 779 
 824 
 1800 
 1002 
 1210 
 1227 
 
 120 
 
 973 
 1049 
 2260 
 1307 
 1641 
 1802 
 
 150 
 
 1133 
 1240 
 2630 
 1580 
 1988 
 2154 
 
 180 
 
 1244 
 1423 
 2820 
 1752 
 2166 
 2386 
 
 210 
 
 240 
 
 1297 
 1659 
 
 1898 
 2388 
 2680 
 
 270 
 
 1311 
 1705 
 
 1927 
 2443 
 2719 
 
 300 
 
 1328 
 1753 
 
 1952 
 2466 
 2752 
 
 330 
 
 1344 
 1800 
 
 1962 
 2485 
 2789 
 
 360 
 
 1359 
 1806 
 3240 
 1971 
 2507 
 2826 
 
 Polish 
 Himalayan 
 Flemish 
 Fi, PXH 
 Fi. PXF 
 
 20 
 5 
 2 
 25 
 27 
 16 
 
 1284 
 1536 
 2940 
 1854 
 2283 
 2553 
 
 F,. PXH 
 
 
 TABLE 2. Comparative weights in grams of the two sexes in the groups of rabbits studied. 
 
 Group. 
 
 No. of males. 
 
 Av. wt. males. 
 
 No. of females. 
 
 Av. wt. females. 
 
 Difference. 
 
 Polish 
 
 10 
 
 1424 
 
 10 
 
 1403 
 
 - 21 
 
 Himalayan. 
 
 1 
 
 1880 
 
 5 
 
 1870 
 
 - 10 
 
 F,, PXH.. 
 
 15 
 
 1957 
 
 10 
 
 2005 
 
 + 48 
 
 F,, PXH.. 
 
 23 
 
 1560 
 
 27 
 
 1704 
 
 + 144 
 
 Fi, PXF... 
 
 14 
 
 2469 
 
 13 
 
 2545 
 
 + 76 
 
 F,, PXF... 
 
 61 
 
 2080 
 
 52 
 
 2176 
 
 + 96 
 
 F,, HXF.. 
 
 8 
 
 2694 
 
 8 
 
 2886 
 
 + 192 
 
 F,, HXF.. 
 
 30 
 
 2401 
 
 32 
 
 2531 
 
 + 130
 
 30 GENETIC STUDIES OF RABBITS AND RATS. 
 
 TABLE 3. Clarification at to weight of the several groups of rabbits studied. 
 
 (Claw 10 includes weights 1.000 to 1,099 grams; class 11 includes weights 1,100 to 1,199, 
 etc. There are no data for columns 11, 32, 33, 35 to 39, and they are therefore omitted.] 
 
 Group. 
 
 10 
 
 1'2 
 
 13 
 
 14 
 
 15 
 
 10 
 
 1 
 1 
 
 a 
 
 10 
 2 
 
 17 
 
 IS 
 
 19 
 
 20 
 
 21 
 
 22 
 
 23 
 
 24 
 
 25 
 
 26 
 
 27 
 
 28 
 
 29 
 
 30 
 
 31 
 
 34 
 
 40 
 
 1 
 
 Average in 
 grams. 
 
 1 
 
 OQ 
 
 Polish 
 Himalayan. 
 Flemish 
 
 
 (> 
 1 
 
 3 
 8 
 
 1 
 
 '> 
 
 3 
 
 1 
 7 
 
 1 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 20 
 6 
 3 
 25 
 50 
 27 
 112 
 16 
 62 
 
 1404 
 1866 
 3646 
 1973 
 1652 
 2512 
 2126 
 2827 
 2472 
 
 142 
 
 218 
 233 
 198 
 257 
 162 
 230 
 
 2 
 
 
 1 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 '2 
 
 Fi. PXH... 
 Ft. PXH... 
 F,, PXF... 
 Ft PXF 
 
 1 
 
 i 
 
 7 
 13 
 
 4 
 
 7 
 
 9 
 
 6 
 4 
 
 10 
 
 i 
 
 i 
 
 1C 
 
 i 
 
 3 
 
 18 
 7 
 
 2 
 
 1 
 ] 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 11 
 
 4 
 
 5 
 
 12 
 
 7 
 
 5 
 
 13 
 
 15 
 
 4 
 
 4 
 
 10 
 
 5 
 1 
 
 2 
 
 
 
 3 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 F HXF 
 
 
 
 
 
 5 
 5 
 
 2 
 
 3 
 
 3 
 3 
 
 2 
 
 1 
 
 
 
 Ft HXF 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 TABLE 4. Statistics of variation in millimeters of ear-length in the several groups of 
 Pi, Fi, and F t rabbits studied. 
 
 Race. 
 
 No. 
 
 Range. 
 
 Average. 
 
 Standard 
 deviation. 
 
 Intermediate 
 between 
 parent races. 
 
 Polish 
 
 23 
 
 81 to 88 
 
 83 6 
 
 
 
 Himalayan 
 
 6 
 
 92 to 97 
 
 94 8 
 
 
 
 Flemish 
 Pi, P X H 
 
 3 
 25 
 
 143 to 147 
 90 to 98 
 
 145.3 
 94 9 
 
 1 74 
 
 89 2 
 
 Ft, P X H 
 
 65 
 
 85 to 99 
 
 92 
 
 3 62 
 
 89 2 
 
 F,, H X F 
 Ft.H X F 
 
 17 
 70 
 
 112 to 119 
 106 to 129 
 
 115.6 
 115 7 
 
 2.08 
 5 85 
 
 120.0 
 120 
 
 Fi, P X F 
 
 27 
 
 103 to 116 
 
 109 3 
 
 3 76 
 
 114 4 
 
 Ft, P X F 
 
 131 
 
 93 to 122 
 
 107 
 
 6 05 
 
 114 4 
 
 
 
 
 
 
 
 TABLE 5. Comparative average ear-length in 
 millimeters of males and females in the 
 groups of rabbits studied. 
 
 Cross. 
 
 Males. 
 
 Females. 
 
 Pi. P X H... 
 
 95.4 
 
 94.2 
 
 Ft, P XH.... 
 
 92.5 
 
 91.6 
 
 Pi, H X F. . . . 
 
 114.5 
 
 116.6 
 
 F,,H X F.... 
 
 115.7 
 
 116.5 
 
 F,. P X F.... 
 
 109.1 
 
 107.7 
 
 F,, P X F. ... 
 
 106.9 
 
 107.1
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 31 
 
 TABLE 6. Variation of skull-length in the several groups of rabbits studied. 
 [All measurements in millimeters.] 
 
 Race. 
 
 No. 
 
 Range. 
 
 Average. 
 
 Standard 
 deviation. 
 
 Intermediate 
 between 
 parent races. 
 
 Polish 
 
 21 
 
 63 to 69 
 
 65 7 
 
 
 
 
 g 
 
 66 to 72 5 
 
 68 9 
 
 
 
 Flemish 
 
 5 
 
 82.5 to 88 
 
 85.5 
 
 
 
 
 F,, P XH 
 
 25 
 
 62 to 74. 5 
 
 70.2 
 
 2.16 
 
 67.3 
 
 F. P XH 
 
 53 
 
 65 to 75 
 
 68.9 
 
 2.25 
 
 67.3 
 
 F lf H X F 
 
 16 
 
 76 to 82. 5 
 
 78.9 
 
 1.79 
 
 77.2 
 
 Fi, H X F 
 
 64 
 
 69. 5 to 83. 5 
 
 76.5 
 
 2.85 
 
 77.2 
 
 Pi, P X F 
 
 27 
 
 73 to 79. 5 
 
 75.5 
 
 1.18 
 
 75.8 
 
 F,, P X F 
 
 125 
 
 63. 5 to 80 
 
 73.1 
 
 3.15 
 
 75.6 
 
 TABLE 7. Variation in millimeters of anterior skull-width in the 
 several groups of rabbits studied. 
 
 Race. 
 
 No. 
 
 Range. 
 
 Average. 
 
 Standard 
 deviation. 
 
 Polish 
 
 20 
 
 36 to 41 
 
 37 6 
 
 .25 
 
 Himalayan 
 
 8 
 
 35 to 39 5 
 
 37 
 
 07 
 
 Flemish 
 
 5 
 
 43 5 to 47 
 
 45 3 
 
 
 F,,P XH 
 F,, P XH 
 Fi.H X F 
 F, H X F 
 Fi, P X F 
 Fj, P X F 
 
 25 
 53 
 17 
 64 
 27 
 125 
 
 36. 5 to 41. 5 
 35. 5 to 40. 5 
 39. 5 to 46 
 38. 5 to 45 
 40 to 44 
 37 to 45 
 
 39.4 
 38.2 
 42.9 
 41.6 
 42.3 
 40.8 
 
 .15 
 .35 
 .40 
 .36 
 .72 
 1.36 
 
 
 
 
 
 
 TABLE 8. Variation in millimeters of posterior skull-width in the several 
 groups of rabbits studied. 
 
 Race. 
 
 No. 
 
 Range. 
 
 Average. 
 
 Standard 
 deviation. 
 
 Polish 
 Himalayan 
 
 20 
 8 
 
 36 to 40. 5 
 37 to 40 
 
 38.0 
 37.9 
 
 0.96 
 1.09 
 
 Flemish 
 F lf P X H 
 
 5 
 25 
 
 44 to 47 
 36 5 to 42 5 
 
 45.4 
 39.5 
 
 1.12 
 .33 
 
 F 2 , P X H 
 
 52 
 
 35. 5 to 40 
 
 38.1 
 
 .17 
 
 F,,H X F 
 Fi, H X F 
 F,, P X F 
 F,, P X F 
 
 17 
 64 
 27 
 125 
 
 40. 5 to 44. 5 
 38 to 45 
 39. 5 to 44 
 37 to 44. 5 
 
 1 43.2 
 42.0 
 42.2 
 40.8 
 
 .95 
 .36 
 .32 
 .20
 
 32 GENETIC STUDIES OF RABBITS AND RATS. 
 
 TABLE 9. Variation in millimeters of length of tibia in the several groups of rabbits studied. 
 
 Race. 
 
 No. 
 
 Bang*. 
 
 Average. 
 
 Standard 
 deviation. 
 
 Intermediate 
 between 
 parent races. 
 
 Polish 
 
 21 
 
 79 to 89 
 
 83.9 
 
 2.26 
 
 
 Himalayan 
 
 8 
 
 92 to 96 
 
 93.9 
 
 1.41 
 
 
 
 5 
 
 105 to 116 
 
 111.0 
 
 
 
 Fj. P X H 
 
 25 
 
 86 to 96 
 
 W.8 
 
 2.38 
 
 88.9 
 
 FI P X H 
 
 54 
 
 80 to 96 
 
 89.8 
 
 3 39 
 
 88 it 
 
 Fi. H X F 
 
 17 
 
 95 to 105 
 
 99.0 
 
 2.44 
 
 102.4 
 
 FI. H X F 
 
 60 
 
 90 to 105 
 
 97.3 
 
 3.10 
 
 102.4 
 
 Fi. P X F 
 
 27 
 
 92 to 100 
 
 96.2 
 
 2.27 
 
 97.4 
 
 F f . P X F 
 
 127 
 
 82 to 104 
 
 93.4 
 
 4.75 
 
 97.4 
 
 
 
 
 
 
 
 TABLE 10. Variation in millimeters of length of femur in the several groups of 
 rabbits studied. 
 
 Race. 
 
 No. 
 
 Range. 
 
 Average. 
 
 Standard 
 deviation. 
 
 Intermediate 
 between 
 parent races. 
 
 Poliah 
 Himalayan . . 
 
 20 
 8 
 
 68 to 76 
 77 to 82 
 
 72.3 
 79 5 
 
 1.71 
 1 83 
 
 
 Flemish 
 
 5 
 
 94 to 102 
 
 97 6 
 
 
 
 Fi, P X H 
 
 25 
 
 73 to 82 
 
 78 2 
 
 1 92 
 
 75 9 
 
 Ft, P X H 
 
 54 
 
 68 to 80 
 
 76 2 
 
 2 49 
 
 75 9 
 
 Fj. H X F 
 
 17 
 
 84 to 91 
 
 87 2 
 
 1 61 
 
 88 5 
 
 Fj. H X F 
 
 6G 
 
 78 to 90 
 
 84 7 
 
 2 86 
 
 88 5 
 
 Fj, P X F 
 
 27 
 
 80 to 86 
 
 83 3 
 
 1 67 
 
 84 9 
 
 F,, P X F 
 
 126 
 
 71 to 88 
 
 80 4 
 
 3 83 
 
 84 9 
 
 
 
 
 
 
 
 TABLE 11. Variation in millimeters of length of humerus in the several groups of 
 rabbits studied. 
 
 Race. 
 
 No. 
 
 Range. 
 
 Average. 
 
 Standard 
 deviation. 
 
 Intermciliatc 
 between 
 parent races. 
 
 Polish 
 
 21 
 
 54 5 to 60 5 
 
 57 7 
 
 1 39 
 
 
 Himalayan 
 
 8 
 
 61 5 to 63 5 
 
 63 
 
 75 
 
 
 Flemish. . 
 
 4 
 
 73 to 71 5 
 
 75 
 
 
 
 1.. P X H 
 I. P X H 
 
 25 
 51 
 
 59 to 65 
 
 VI ."i to 64 5 
 
 62.8 
 60 9 
 
 1 51 
 2 37 
 
 60.3 
 60 3 
 
 FI. H X F 
 
 17 
 
 66 to 71 
 
 68 8 
 
 
 
 F. H X F 
 F,. P X F 
 Ft. P X F. 
 
 f.6 
 27 
 126 
 
 62. 5 to 71. 5 
 63. 5 to 68. 5 
 56 to 70 6 
 
 67.3 
 66 2 
 
 no o 
 
 2.26 
 1.20 
 
 69.0 
 66.3 
 
 
 
 
 

 
 GENETIC STUDIES OF RABBITS AND RATS. 33 
 
 TABLE 12. Correlation of ear-length with weight. 
 
 * 
 
 * 
 
 J3 ?. 
 
 *.s a 
 
 Ear-length in millimeters. 
 
 1 
 
 80 
 
 83 
 
 80 
 
 89 
 
 92 
 
 95 
 
 98 
 
 101 
 
 104 
 
 107 
 
 110 
 
 113 
 
 110 
 
 119 
 
 122 
 
 125 
 
 128 
 
 131 
 
 134 
 
 137 
 
 140 
 
 143 
 
 140 
 
 10 
 
 11 
 
 12 
 13 
 14 
 15 
 16 
 17 
 18 
 19 
 20 
 21 
 22 
 23 
 24 
 25 
 26 
 27 
 28 
 29 
 30 
 31 
 32 
 33 
 34 
 35 
 36 
 37 
 38 
 39 
 40 
 
 Total . 
 
 2 
 1 
 3 
 
 1 
 
 3 
 2 
 3 
 3 
 
 1 
 
 2 
 
 3 
 1 
 
 i 
 
 3 
 
 1 
 
 2 
 3 
 1 
 1 
 1 
 
 1 
 
 2 
 
 4 
 4 
 4 
 6 
 3 
 1 
 1 
 1 
 
 1 
 2 
 1 
 
 4 
 4 
 (j 
 6 
 3 
 2 
 2 
 1 
 
 1 
 
 i 
 
 4 
 3 
 
 2 
 3 
 
 i 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 G 
 9 
 12 
 12 
 16 
 22 
 23 
 22 
 24 
 29 
 18 
 28 
 31 
 23 
 15 
 13 
 8 
 4 
 3 
 
 
 
 
 
 
 
 
 
 ::: 
 
 1 
 
 4 
 2 
 5 
 4 
 1 
 4 
 6 
 
 1 
 1 
 
 
 
 
 
 
 
 
 2 
 2 
 3 
 3 
 
 1 
 1 
 
 1 
 1 
 
 1 
 
 1 
 2 
 
 4 
 7 
 5 
 6 
 6 
 2 
 3 
 
 1 
 
 i 
 
 3 
 
 7 
 
 5 
 
 8 
 6 
 2 
 4 
 
 1 
 2 
 6 
 1 
 3 
 7 
 5 
 3 
 3 
 
 1 
 1 
 
 1 
 
 "3 
 3 
 3 
 2 
 3 
 2 
 4 
 2 
 1 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 2 
 5 
 4 
 
 
 1 
 
 
 
 
 
 
 
 
 1 
 1 
 1 
 
 i 
 
 1 
 
 i 
 
 i 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 i 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 i 
 
 1 
 3-2-2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ~ 
 
 1 
 
 6 
 
 13 
 
 8 
 
 14 
 
 20 
 
 r,i 
 
 16 
 
 29 
 
 14 
 
 38 
 
 38 
 
 33 
 
 24 
 
 16 
 
 5 
 
 3 
 
 3 
 
 
 
 
 2 
 
 
 
 
 Mean ear-length, 105.350.43. S. D. ear-length, 3.860.10. 
 
 Mean weight, 2 14. 15 16.8. S. D. weight, 448.6 11. 9. r, 0.830 0.011. 
 
 TABLE 13. Correlation of ear-length with skull-length. 
 
 Skull- 
 length. 
 
 80 
 
 Ear-length in millimeters. 
 
 I 
 
 6 
 
 16 
 22 
 43 
 55 
 45 
 58 
 U 
 24 
 10 
 3 
 2 
 
 83 
 
 86 
 
 1 
 3 
 
 89 
 
 1 
 
 4 
 4 
 2 
 1 
 
 02 
 
 95 
 
 98 
 
 101 
 
 104 
 
 107 
 
 110 
 
 na 
 
 110 
 
 119 
 
 122 
 
 125 
 
 128 
 
 , 
 
 134 
 
 137 
 
 140 
 
 143 
 
 146 
 
 62 
 64 
 66 
 68 
 70 
 72 
 74 
 76 
 78 
 80 
 82 
 84 
 86 
 
 Total . 
 
 2 
 2 
 
 2 
 
 1 
 
 7 
 2 
 3 
 
 5 
 
 12 
 7 
 3 
 
 1 
 
 a 
 
 8 
 17 
 2 
 3 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 7 
 
 1 
 
 1 
 
 4 
 2 
 3 
 
 14 
 6 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 10 
 4 
 2 
 
 3 
 3 
 8 
 16 
 9 
 1 
 
 5 
 6 
 
 12 
 14 
 2 
 2 
 
 3 
 
 8 
 12 
 9 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 8 
 4 
 5 
 3 
 
 
 
 
 
 
 
 
 
 
 
 
 9 
 
 
 
 
 
 
 
 
 
 3 
 7 
 5 
 2 
 
 
 
 
 
 
 
 
 
 
 2 
 1 
 
 1 
 
 1 
 1 
 1 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 1 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 3 
 
 t 
 
 
 
 ~~ 
 
 1 
 
 6 
 
 13 
 
 X 
 
 14 
 
 27 
 
 34 
 
 17 
 
 3(\ 
 
 17 
 
 40 
 
 41 
 
 82 
 
 n 
 
 17 
 
 A 
 
 3 
 
 
 
 2 
 
 7 
 
 Mean ear-length, 105.45 0.42. S. D. ear-length, 11. 46 0.28. 
 
 Mean skull-length, 73.030.16. S. D. skull-length, 4.420.11. r, 0.8360.011.
 
 34 
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 TABUS 14. Correlation of ear-length with humerus-length. 
 
 H 
 
 Ear-length. 
 
 | 
 
 SO 
 
 1 
 
 5 
 
 83 
 
 SO 
 
 89 
 
 1 
 
 1 
 4 
 
 92 
 
 95 
 
 98 
 
 101 
 
 104 
 
 107 
 
 110 
 
 113 
 
 116 
 
 119 
 
 122 
 
 125 
 
 128 
 
 131 
 
 134 
 
 i:57 
 
 140 
 
 143 
 
 146 
 
 64 
 
 60 
 68 
 00 
 02 
 04 
 00 
 08 
 70 
 72 
 74 
 70 
 
 Total. 
 
 1 
 4 
 1 
 
 2 
 
 ? 
 
 1 
 
 ; 
 
 | 
 
 2 
 ? 
 
 i 
 
 i 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 4 
 17 
 
 23 
 41 
 78 
 67 
 58 
 32 
 16 
 1 
 1 
 1 
 
 
 
 
 
 
 
 
 
 
 
 j 
 
 
 
 
 
 
 
 
 
 
 
 :: 
 
 3 
 
 3 
 
 4 
 
 3 
 
 7 
 14 
 
 3 
 21 
 
 7 
 
 4 
 
 5 
 3 
 
 6 
 13 
 9 
 
 6 
 3 
 
 7 
 2 
 
 4 
 12 
 10 
 11 
 2 
 1 
 
 1 
 
 6 
 19 
 12 
 3 
 
 
 
 
 
 
 
 
 
 
 7 
 14 
 8 
 7 
 
 4 
 
 9 
 8 
 2 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 8 
 6 
 3 
 
 1 
 
 3 
 
 
 j 
 
 
 
 
 
 
 
 
 
 
 
 
 
 3 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 "l 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 7 
 
 13 
 
 8 
 
 13 
 
 27 
 
 34 
 
 16 
 
 30 
 
 18 
 
 41 
 
 41 
 
 36 
 
 24 
 
 17 
 
 5 
 
 3 
 
 3 
 
 
 
 
 
 1 
 
 2 
 
 339 
 
 
 
 
 Mean ear-length, 105.46 0.41. S. D. ear-length, 11. 46 0.29. 
 
 Mean humenu, 64. 1 7 0. 13. 8. D. humerus, 3.73 0.09. r, 0.823 0.01 1 . 
 
 TABLE 15. Correlation of ear-length with femur-length. 
 
 ?emur- 
 
 length. 
 
 Ear-length. 
 
 1 
 
 SO 
 
 S3 
 
 hO 
 
 S9 
 
 J2 
 
 95 
 
 98 
 
 101 
 
 104 
 
 107 
 
 110 
 
 113 
 
 11C 
 
 119 
 
 122 
 
 125 
 
 128 
 
 131 
 
 134 
 
 137 
 
 140 
 
 143 
 
 146 
 
 08 
 70 
 72 
 74 
 70 
 78 
 80 
 82 
 84 
 80 
 88 
 00 
 02 
 04 
 00 
 08 
 
 Total 
 
 2 
 3 
 2 
 
 1 
 1 
 9 
 1 
 1 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 4 
 6 
 24 
 23 
 48 
 48 
 48 
 55 
 31 
 30 
 21 
 2 
 
 1 
 343 
 
 2 
 5 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 3 
 1 
 
 7 
 
 1 
 
 6 
 7 
 
 10 
 2 
 
 2 
 2 
 9 
 11 
 
 7 
 2 
 
 3 
 1 
 8 
 2 
 1 
 | 
 
 1 
 1 
 | 
 7 
 I 
 1 
 2 
 
 2 
 4 
 I 
 
 6 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 4 
 11 
 
 8 
 9 
 5 
 
 4 
 
 1 
 3 
 4 
 10 
 11 
 7 
 6 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 4 
 10 
 6 
 11 
 4 
 \ 
 
 2 
 7 
 
 4 
 4 
 7 
 
 6 
 5 
 
 4 
 1 
 
 i 
 i 
 
 2 
 2 
 
 2 
 1 
 
 1 
 2 
 
 
 
 
 
 
 i 
 i 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 7 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 :w 
 
 17 
 
 30 
 
 
 
 41 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 
 13 
 
 8 
 
 14 
 
 28 
 
 17 
 
 43 
 
 36 
 
 24 
 
 17 
 
 6 
 
 3 
 
 3 
 
 
 
 
 
 1 
 
 Mean ear-length, 106.46 0.41. 8. D. ear-length, 11.47 0.29. 
 Mean fcmur, 80.730.18. 8. D. femur, 6.000.12. r, 0.8280.011.
 
 GENETIC STUDIES OP RABBITS AND RATS. 
 TABLE 16. Correlation of ear-length with tibia-length. 
 
 35 
 
 Tibia- 
 length. 
 
 Ear-length. 
 
 1 
 
 80 
 
 83 
 
 86 
 
 89 
 
 92 
 
 95 
 
 98 
 
 101 
 
 i 
 
 3 
 5 
 4 
 6 
 5 
 3 
 3 
 
 104 
 
 107 
 
 110 
 
 113 
 
 116 
 
 119 
 
 122 
 
 125 
 
 128 
 
 131 
 
 134 
 
 137 
 
 140 
 
 143 
 
 140 
 
 80 
 82 
 84 
 86 
 88 
 90 
 92 
 94 
 96 
 98 
 100 
 102 
 104 
 106 
 108 
 110 
 112 
 
 Total. 
 
 3 
 
 4 
 
 1 
 1 
 7 
 3 
 1 
 
 1 
 
 1 
 
 2 
 4 
 
 1 
 
 5 
 1 
 4 
 3 
 
 1 
 
 2 
 3 
 4 
 8 
 6 
 4 
 
 i 
 
 i 
 i 
 
 2 
 6 
 10 
 
 8 
 5 
 
 3 
 
 4 
 4 
 3 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 5 
 10 
 13 
 22 
 29 
 42 
 65 
 54 
 41 
 37 
 23 
 7 
 4 
 
 3 
 1 
 5 
 3 
 
 4 
 
 i 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 3 
 8 
 10 
 6 
 5 
 5 
 2 
 2 
 
 1 
 
 4 
 3 
 
 9 
 7 
 8 
 9 
 
 4 
 8 
 6 
 7 
 6 
 3 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 4 
 5 
 7 
 7 
 
 "5 
 5 
 2 
 4 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 "3 
 2 
 
 i 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 2 
 
 1 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 ... 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 1 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 7 
 
 13 
 
 8 
 
 15 
 
 27 
 
 34 
 
 17 
 
 30 
 
 17 
 
 43 
 
 41 
 
 36 
 
 24 
 
 17 
 
 6 
 
 3 
 
 3 
 
 
 
 
 
 1 
 
 1 
 
 344 
 
 
 
 
 
 Mean ear-length, 105.42 0.41. S. D. ear-length, 11. 48 0.29. 
 Mean tibia, 93.64 0.19. S. D. tibia, 5.27 0.13. r,. 0.741 0.016. 
 
 TABLE 17. Correlation of weight with skull-length. 
 
 Skull- 
 length. 
 
 Weight in hektograms. 
 
 Total. 
 
 10 
 
 11 
 
 12 
 
 13 
 
 14 
 
 15 
 
 16 
 
 17 
 
 18 
 
 19 
 
 20 
 
 21 
 
 22 
 
 23 
 
 24 
 
 25 
 
 26 
 
 27 
 
 28 
 
 29 
 
 30 
 
 34 
 
 40 
 
 62 
 64 
 66 
 68 
 70 
 72 
 74 
 76 
 78 
 80 
 82 
 84 
 86 
 
 Total. 
 
 
 
 ? 
 
 
 1 
 
 
 1 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 
 i 
 
 5 
 13 
 20 
 39 
 51 
 43 
 56 
 62 
 23 
 11 
 2 
 2 
 
 1 
 
 
 2 
 1 
 
 4 
 
 2 
 3 
 
 2 
 5 
 2 
 1 
 1 
 
 1 
 4 
 5 
 
 2 
 
 3 
 
 4 
 
 4 
 2 
 
 1 
 1 
 
 
 
 
 
 
 
 
 
 
 
 2 
 7 
 1 
 2 
 1 
 
 2 
 
 4 
 
 1 
 
 i 
 i 
 
 2 
 
 i 
 i 
 i 
 
 3 
 9 
 8 
 2 
 
 's 
 
 8 
 
 5 
 
 1 
 
 1 
 5 
 10 
 4 
 
 10 
 6 
 4 
 3 
 
 i 
 
 6 
 6 
 
 12 
 2 
 
 3 
 
 30 
 
 
 ... 
 
 
 
 1 
 
 5 
 7 
 5 
 
 6 
 8 
 7 
 1 
 2 
 
 2 
 
 5 
 
 7 
 13 
 4 
 1 
 
 2 
 6 
 7 
 6 
 2 
 
 5 
 4 
 3 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 5 
 
 9 
 
 12 
 
 12 
 
 16 
 
 23 
 
 22 
 
 21 
 
 24 
 
 18 
 
 26 
 
 32 
 
 23 
 
 u 
 
 13 
 
 8 
 
 4 
 
 3 
 
 2 
 
 i 
 
 318 
 
 Mean weight, 2,141.016.9. S. D. weight, 447.011.9. 
 Mean skull-length, 73.17 0.16. S. D. skull-length, 4.380.11. 
 
 r, 0.8520.010.
 
 36 
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 TABLE 18. Correlation of weight with humerus. 
 
 Hum*. 
 
 Weight. 
 
 Total. 
 
 rua. 
 
 10 
 
 11 
 
 1-2 
 
 13 
 
 14 
 
 i:> 
 
 If, 
 
 17 
 
 IN 
 
 19 
 
 M 
 
 21 
 
 n 
 
 23 
 
 24 
 
 25 
 
 26 
 
 27 
 
 28 
 
 M 
 
 M 
 
 34 
 
 40 
 
 64 
 66 
 
 68 
 60 
 62 
 64 
 66 
 68 
 70 
 72 
 74 
 76 
 
 Total. 
 
 
 
 
 1 
 
 
 o 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 3 
 16 
 21 
 39 
 72 
 59 
 58 
 31 
 16 
 1 
 1 
 1 
 
 i 
 
 
 3 
 I 
 
 1 
 
 1 
 2 
 2 
 1 
 
 4 
 4 
 1 
 3 
 
 1 
 
 '2 
 2 
 1 
 
 i 
 
 5 
 1 
 
 4 
 
 1 
 6 
 
 7 
 8 
 2 
 
 1 
 1 
 7 
 11 
 I 
 
 
 
 
 
 
 
 
 7 
 9 
 4 
 
 
 
 
 
 
 
 
 4 
 9 
 1 
 
 4 
 
 2 
 6 
 
 14 
 8 
 1 
 
 8 
 
 7 
 3 
 
 6 
 4 
 11 
 3 
 2 
 
 6 
 
 7 
 10 
 4 
 5 
 
 
 6 
 9 
 
 2 
 
 2 
 
 4 
 6 
 2 
 
 2 
 6 
 6 
 1 
 
 1 
 3 
 3 
 1 
 
 2 
 
 2 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 1 
 
 :;j 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 28 
 
 
 
 
 
 
 
 
 i 
 
 
 I 
 
 7 
 
 13 
 
 11 
 
 I.', 
 
 23 
 
 2-2 
 
 I'D 
 
 IB 
 
 30 
 
 18 
 
 27 
 
 n 
 
 14 
 
 13 
 
 s 
 
 4 
 
 3 
 
 2 
 
 1 
 
 318 
 
 Mean weight, 2,146.5 16.8. S. D. weight. 445.9. 
 
 Mean humerus, 64.260.14. S. D. humerus, 3.750.10. r, 0.8200.012. 
 
 TABLE 19. Correlation of weight with femur. 
 
 Femur. 
 
 Weight. 
 
 Total. 
 
 10 
 
 11 
 
 13 
 
 13 
 
 14 
 
 15 
 
 16 
 
 17 
 
 18 
 
 19 
 
 20 
 
 21 
 
 22 
 
 23 
 
 24 
 
 25 
 
 26 
 
 27 
 
 28 
 
 29 
 
 30 
 
 34 
 
 40 
 
 68 
 70 
 72 
 74 
 76 
 78 
 80 
 82 
 84 
 86 
 88 
 00 
 02 
 04 
 06 
 08 
 
 Total. 
 
 l 
 
 
 1 
 
 a 
 
 2 
 1 
 
 1 
 
 3 
 
 2 
 2 
 
 i 
 
 4 
 2 
 3 
 1 
 
 2 
 
 3 
 4 
 
 2 
 
 1 
 
 4 
 3 
 (i 
 2 
 
 
 
 
 
 
 
 
 4 
 5 
 21 
 22 
 45 
 44 
 43 
 52 
 28 
 29 
 20 
 2 
 
 3 
 9 
 
 Q 
 4 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 3 
 1 
 
 9 
 2 
 2 
 
 1 
 2 
 8 
 7 
 5 
 1 
 1 
 
 6 
 6 
 6 
 9 
 
 4 
 2 
 
 6 
 7 
 8 
 
 1 
 
 3 
 1 
 
 6 
 6 
 
 8 
 3 
 
 2 
 
 2 
 2 
 5 
 10 
 4 
 5 
 2 
 j 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 6 
 7 
 
 4 
 4 
 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 5 
 1 
 
 5 
 3 
 
 3 
 5 
 3 
 
 2 
 2 
 
 3 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 i 
 
 
 
 
 
 
 
 
 
 
 1 
 
 1 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 4 
 
 3 
 
 1 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 14 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 30 
 
 
 
 
 
 
 
 
 
 1-2 
 
 Hi 
 
 
 
 18 
 
 
 
 l 
 
 
 (i 
 
 8 
 
 1-2 
 
 23 
 
 22 
 
 19 
 
 25 
 
 27 
 
 31 
 
 M 
 
 13 
 
 8 
 
 1 
 
 i 
 
 318 
 
 Mean weight, 2,143.016.9. 8. D. weight, 448.011.9. 
 
 Mean femur, 80.800.19. S. D. femur, 5.030.13. r, 0.841 0.011.
 
 GENETIC STUDIES OF RABBITS AND RATS. 37 
 
 TABLE 20. Correlation of weight with tibia. 
 
 Tibia. 
 
 Weight. 
 
 Total. 
 
 10 
 
 11 
 
 12 
 
 13 
 
 14 
 
 15 
 
 16 
 
 17 
 
 18 
 
 19 
 
 20 
 
 21 
 
 22 
 
 23 
 
 24 
 
 25 
 
 26 
 
 27 
 
 28 
 
 29 
 
 30 
 
 34 
 
 40 
 
 80 
 82 
 84 
 86 
 88 
 90 
 92 
 94 
 96 
 98 
 100 
 102 
 104 
 112 
 
 Total . 
 
 i 
 
 
 2 
 1 
 2 
 1 
 
 2 
 
 1 
 2 
 1 
 
 3 
 
 4 
 2 
 2 
 
 1 
 
 2 
 
 1 
 
 1 
 2 
 1 
 1 
 
 1 
 3 
 1 
 3 
 4 
 3 
 1 
 
 
 
 
 
 
 
 1 
 
 5 
 5 
 4 
 5 
 4 
 1 
 
 i 
 i 
 
 2 
 
 7 
 7 
 4 
 4 
 3 
 ? 
 
 1 
 
 3 
 7 
 6 
 6 
 1 
 
 2 
 3 
 
 6 
 1 
 ? 
 
 i 
 
 2 
 2 
 4 
 4 
 
 2 
 3 
 2 
 
 
 
 
 
 4 
 9 
 12 
 
 20 
 27 
 39 
 61 
 48 
 38 
 37 
 22 
 7 
 4 
 2 
 
 2 
 1 
 
 2 
 8 
 3 
 
 4 
 3 
 
 4 
 2 
 6 
 4 
 5 
 
 2 
 2 
 
 7 
 5 
 2 
 2 
 
 2 
 5 
 3 
 7 
 3 
 3 
 1 
 
 2 
 4 
 8 
 2 
 9 
 4 
 1 
 
 1 
 2 
 6 
 5 
 1 
 2 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 1 
 
 1 
 
 
 1 
 ,1 
 
 i 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 6 
 
 
 
 
 
 
 
 20 
 
 25 
 
 
 
 27 
 
 32 
 
 
 
 
 8 
 
 4 
 
 3 
 
 i 
 
 
 7 
 
 13 
 
 12 
 
 16 
 
 23 
 
 22 
 
 30 
 
 18 
 
 23 
 
 14 
 
 13 
 
 2 
 
 1 
 
 320 
 
 Mean weight, 2,143.616.8. S. D. weight, 446.611.9. 
 
 Mean tibia, 93.77 0.20. S. D. tibia, 5.29 0.14. r, 0.758 0.015. 
 
 TABLE 21. Correlation of humerus-length with skull-length. 
 
 
 Humerus-length. 
 
 
 Skull- 
 length. 
 
 
 Total. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 54 
 
 56 
 
 58 
 
 60 
 
 62 
 
 64 
 
 66 
 
 68 
 
 70 
 
 72 
 
 74 
 
 76 
 
 
 62 
 
 
 2 
 
 1 
 
 
 
 
 
 
 
 
 
 
 5 
 
 64 
 
 1 
 
 5 
 
 5 
 
 5 
 
 
 
 
 
 
 
 
 
 16 
 
 66 
 
 4 
 
 4 
 
 7 
 
 3 
 
 7 
 
 
 
 
 
 
 
 
 25 
 
 68 
 
 
 5 
 
 I 
 
 13 
 
 14 
 
 2 
 
 
 
 
 
 
 
 42 
 
 70 
 
 
 
 
 14 
 
 23 
 
 14 
 
 3 
 
 
 
 
 
 
 54 
 
 72 
 
 
 
 
 5 
 
 22 
 
 11 
 
 8 
 
 
 1 
 
 
 
 
 47 
 
 74 
 
 
 
 1 
 
 2 
 
 9 
 
 23 
 
 18 
 
 3 
 
 2 
 
 
 
 
 58 
 
 76 
 
 
 
 
 
 3 
 
 12 
 
 21 
 
 11 
 
 5 
 
 
 
 
 52 
 
 78 
 
 
 
 
 
 
 2 
 
 6 
 
 12 
 
 4 
 
 
 
 
 24 
 
 80 
 
 
 
 
 
 
 
 4 
 
 4 
 
 2 
 
 
 
 
 10 
 
 82 
 
 
 
 
 
 
 
 
 1 
 
 2 
 
 1 
 
 
 
 4 
 
 84 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 1 
 
 2 
 
 86 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 1 
 
 Total . 
 
 
 
 24 
 
 
 78 
 
 64 
 
 60 
 
 31 
 
 
 
 1 
 
 1 
 
 
 5 
 
 16 
 
 42 
 
 16 
 
 2 
 
 340 
 
 Mean humerus, 64. 16 0.13. S. D. humerus, 3.77 0.09. 
 
 Mean skull, 72.960.16. S. D. skull, 4.460.11. r, 0.834 0.011.
 
 38 GENETIC STUDIES OF RABBITS AND RATS. 
 
 TABLE 22. Correlation of femur-length with skull-length. 
 
 Skull- 
 length. 
 
 Femur-length. 
 
 Total. 
 
 68 
 
 70 
 
 72 
 
 74 
 
 76 
 
 78 
 
 80 
 
 82 
 
 84 
 
 86 
 
 88 
 
 90 
 
 92 
 
 94 
 
 96 
 
 98 
 
 100 
 
 102 
 
 62 
 64 
 66 
 
 68 
 70 
 72 
 74 
 76 
 78 
 80 
 82 
 84 
 86 
 88 
 
 Total. 
 
 1 
 1 
 2 
 
 1 
 
 1 
 
 4 
 
 3 
 9 
 
 7 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 5 
 16 
 25 
 43 
 54 
 47 
 58 
 53 
 24 
 10 
 4 
 2 
 1 
 1 
 
 4 
 4 
 11 
 2 
 
 1 
 
 1 
 
 8 
 12 
 15 
 10 
 2 
 
 i 
 
 9 
 16 
 12 
 6 
 2 
 
 4 
 15 
 9 
 16 
 
 4 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 6 
 
 10 
 18 
 20 
 1 
 
 3 
 
 9 
 10 
 6 
 2 
 
 1 
 4 
 14 
 9 
 
 i 
 
 2 
 I 
 
 6 
 
 7 
 2 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 1 
 1 
 
 
 
 
 i 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ... 
 
 
 4 
 
 6 
 
 25 
 
 23 
 
 48 
 
 46 
 
 49 
 
 55 
 
 30 
 
 29 
 
 21 
 
 2 
 
 2 
 
 1 
 
 1 
 
 
 i 
 
 343 
 
 Mean femur, 80.80 0.19. 8. D. femur, 5.20 0.13. 
 
 Mean skull, 73.060.16. S. D. skull, 4.530.11. r, 0.871 0.008. 
 
 TABLE VS. Correlation of tibia-length with skull-length. 
 
 Skull- 
 length. 
 
 Tibia-length. 
 
 Total. 
 
 80 
 
 82 
 
 84 
 
 86 
 
 88 
 
 90 
 
 92 
 
 94 
 
 96 
 
 98 
 
 100 
 
 102 
 
 104 
 
 106 
 
 112 
 
 116 
 
 62 
 64 
 66 
 68 
 70 
 72 
 74 
 76 
 78 
 80 
 
 84 
 86 
 88 
 
 Total. 
 
 1 
 1 
 2 
 
 2 
 2 
 
 4 
 3 
 
 1 
 
 7 
 4 
 1 
 1 
 
 1 
 3 
 5 
 5 
 2 
 5 
 
 2 
 2 
 13 
 2 
 4 
 3 
 1 
 
 .... 
 
 2 
 13 
 13 
 8 
 
 4 
 2 
 
 'e 
 
 4 
 17 
 13 
 9 
 5 
 1 
 
 
 
 
 
 
 
 
 
 5 
 16 
 25 
 43 
 54 
 46 
 58 
 53 
 24 
 10 
 14 
 2 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 4 
 13 
 5 
 18 
 13 
 
 
 
 
 
 
 
 
 
 5 
 5 
 10 
 13 
 
 7 
 1 
 
 1 
 5 
 7 
 12 
 7 
 3 
 
 i 
 
 7 
 4 
 5 
 5 
 
 
 
 
 
 
 
 
 2 
 4 
 1 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 j 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 . 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 4 
 
 11 
 
 14 
 
 21 
 
 27 
 
 43 
 
 55 
 
 53 
 
 41 
 
 35 
 
 23 
 
 7 
 
 4 
 
 1 
 
 2 
 
 1 
 
 342 
 
 Mean tibia, 93.740.20. S. D. tibia, 5.450.14. 
 
 Mean kulJ. 73.060.16. 8. D. skull, 4.540.11. r, 0.8060.015.
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 TABLE 24. Correlation of femur with humerus, all group* included. 
 
 39 
 
 Hume- 
 
 rus. 
 
 Femur. 
 
 Total. 
 
 68 
 
 70 
 
 72 
 
 74 
 
 76 
 
 78 
 
 80 
 
 82 
 
 84 
 
 86 
 
 88. 
 
 90 
 
 92 
 
 94 
 
 96 
 
 98 
 
 54 
 56 
 58 
 60 
 62 
 64 
 66 
 68 
 70 
 72 
 74 
 76 
 
 Total . 
 
 3 
 1 
 
 1 
 5 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 4 
 18 
 24 
 41 
 79 
 64 
 61 
 32 
 16 
 2 
 1 
 
 10 
 13 
 2 
 
 2 
 10 
 11 
 
 'is' 
 
 28 
 2 
 
 V 
 
 29 
 
 8 
 
 
 
 
 2 
 7 
 14 
 6 
 
 1 
 11 
 
 8 
 
 
 
 
 
 1 
 
 18 
 26 
 
 4 
 
 4 
 25 
 26 
 
 i 
 
 23 
 
 7 
 
 
 
 
 
 
 
 1 
 
 1 
 
 
 
 
 2 
 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 25 
 
 
 
 
 
 
 
 
 
 4 
 
 7 
 
 23 
 
 48 
 
 46 
 
 49 
 
 55 
 
 31 
 
 29 
 
 20 
 
 2 
 
 
 2 
 
 1 
 
 343 
 
 Mean femur, 80.69 0.18. S. D. femur, 5.08dh0.13. 
 
 Mean humerus, 64. 17 0.13. S. D. humorus, 3.78 0.09. r, 0.906 0.006. 
 
 TABLE 25. Correlation of femur with humerus, pure races only. 
 
 Hume- 
 rus. 
 
 Femur. 
 
 Total. 
 
 68 
 
 70 
 
 72 
 
 74 
 
 76 
 
 78 
 
 80 
 
 82 
 
 84 
 
 86 
 
 88 
 
 90 
 
 92 
 
 94 
 
 96 
 
 98 
 
 54 
 56 
 58 
 60 
 62 
 64 
 66 
 68 
 70 
 72 
 74 
 76 
 
 Total . 
 
 1 
 1 
 
 1 
 4 
 1 
 
 6 
 4 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 11 
 6 
 3 
 
 7 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 > 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 
 1 
 
 3 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 
 :: i 
 
 i 
 
 2 
 1 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 2 
 
 6 
 
 11 
 
 1 
 
 4 
 
 1 
 
 3 
 
 
 
 
 
 
 2 
 
 1 
 
 i 
 
 33 
 
 
 
 
 Mean femur, 76.95. S. D. femur, 8.06. 
 
 Mean humenis, 60.95. S. D. humerus, 5.60. r, 0.980 0.004.
 
 40 
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 TABLE 26. Correlation of femur with humerus, F, only. 
 
 Hume- 
 rus. 
 
 Femur. 
 
 Total. 
 
 72 
 
 74 
 
 76 
 
 78 
 
 80 
 
 82 
 
 84 
 
 86 
 
 88 
 
 90 
 
 58 
 60 
 62 
 64 
 66 
 68 
 70 
 
 Total. 
 
 1 
 
 
 
 
 
 e' 
 
 6 
 
 1 
 9 
 1 
 
 
 
 
 1 
 4 
 17 
 14 
 19 
 11 
 3 
 
 2 
 
 6 
 
 1 
 8 
 2 
 
 3 
 
 5 
 
 1 
 
 3 
 6 
 
 
 
 4 
 2 
 
 1 
 
 
 
 
 
 
 .... 
 
 .... 
 
 1 
 
 2 
 
 7 
 
 11 
 
 
 
 12 
 
 11 
 
 9 
 
 6 
 
 1 
 
 N 
 
 Mean femur, 82.64. S. D. femur, 4.08. 
 
 Mean humerus, 65.58. S. D. humeruB, 2.68. r, 0.888 0.017. 
 
 TABLE 27. Correlation of femur with humerus, F t only. 
 
 Hume- 
 
 rus. 
 
 Femur. 
 
 Total. 
 
 68 
 
 70 
 
 72 
 
 74 
 
 76 
 
 78 
 
 80 
 
 82 
 
 84 
 
 86 
 
 88 
 
 90 
 
 64 
 66 
 68 
 60 
 62 
 64 
 66 
 68 
 70 
 
 Total. 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 
 7 
 17 
 34 
 55 
 50 
 42 
 21 
 13 
 
 
 4 
 8 
 
 2 
 9 
 9 
 
 
 
 
 
 
 16 
 20 
 2 
 
 8 
 20 
 6 
 
 12 
 21 
 3 
 
 
 
 
 
 3 
 
 19 
 20 
 
 14 
 6 
 
 
 
 2 
 4 
 8 
 6 
 
 1 
 7 
 6 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 2 
 
 1 
 
 13 
 
 20 
 
 37 
 
 34 
 
 37 
 
 42 
 
 20 
 
 20 
 
 14 
 
 1 
 
 241 
 
 Mean femur, 80.67. S. D. femur. 4.48. 
 
 Mean humenifl. 66.21. S. D. humerus, 3.45. r, 0.878 0.010. 
 
 TABLE 28. Correlation of tibia with humerus. 
 
 Hume- 
 
 
 
 
 
 
 
 
 I'ibia 
 
 
 
 
 
 
 
 
 Total 
 
 rus. 
 
 80 
 
 82 
 
 84 
 
 86 
 
 88 
 
 90 
 
 92 
 
 94 
 
 96 
 
 98 
 
 100 
 
 102 
 
 104 
 
 1M 
 
 112 
 
 
 54... 
 
 ? 
 
 3 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 5 
 
 56 
 
 3 
 
 7 
 
 4 
 
 2 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 17 
 
 58 
 
 
 1 
 
 7 
 
 12 
 
 4 
 
 
 
 
 
 
 
 
 
 
 
 24 
 
 60 
 
 
 
 3 
 
 5 
 
 14 
 
 17 
 
 3 
 
 
 
 
 
 
 
 
 
 42 
 
 62 
 
 
 
 
 3 
 
 7 
 
 19 
 
 29 
 
 15 
 
 4 
 
 2 
 
 
 
 
 
 
 79 
 
 64 . . 
 
 
 
 
 
 2 
 
 5 
 
 19 
 
 20 
 
 13 
 
 6 
 
 
 
 
 
 
 65 
 
 66 
 
 
 
 
 
 
 
 4 
 
 15 
 
 21 
 
 12 
 
 g 
 
 
 
 
 
 60 
 
 68 
 
 
 
 
 
 
 
 
 3 
 
 3 
 
 12 
 
 10 
 
 4 
 
 
 
 
 32 
 
 70 
 
 
 
 
 
 
 
 
 
 
 4 
 
 5 
 
 3 
 
 3 
 
 
 
 16 
 
 72 
 
 
 
 
 
 
 
 
 
 
 
 
 
 j 
 
 1 
 
 
 2 
 
 74 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 76 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 . 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Total. 
 
 6 
 
 11 
 
 14 
 
 22 
 
 28 
 
 41 
 
 66 
 
 53 
 
 42 
 
 36 
 
 23 
 
 7 
 
 4 
 
 1 
 
 2 
 
 344 
 
 Mean tibia, 93.64 0.19. 8. D. tibia. 5.35 0.13. 
 
 Mean humerus. 64.150.13. S. D. humerus. 3.78 () >, 0.9040.006.
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 TABLE 29. Correlation of tibia with femur. 
 
 41 
 
 1 
 
 Tibia. 
 
 1 
 
 80 
 
 82 
 
 84 
 
 86 
 
 88 
 
 90 
 
 92 
 
 94 
 
 96 
 
 98 
 
 100 
 
 102 
 
 104 
 
 106 
 
 112 
 
 116 
 
 68... 
 70... 
 
 72 
 
 2 
 3 
 
 1 
 3 
 
 7 
 
 2 
 11 
 
 7 
 
 
 
 
 
 
 
 
 
 
 
 
 
 3 
 8 
 25 
 23 
 49 
 48 
 49 
 55 
 31 
 29 
 21 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 74.. . 
 
 
 
 1 
 
 10 
 5 
 
 10 
 12 
 5 
 1 
 
 2 
 
 18 
 18 
 5 
 
 
 
 
 
 
 
 
 
 76... 
 78... 
 80... 
 82... 
 84... 
 86 
 
 
 
 14 
 
 17 
 18 
 6 
 
 6 
 17 
 25 
 5 
 
 2 
 7 
 18 
 11 
 2 
 1 
 
 ..... 
 
 6 
 9 
 17 
 4 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 6 
 
 7 
 10 
 
 3 
 3 
 1 
 
 2 
 1 
 
 
 
 
 
 
 88... 
 90... 
 92... 
 94... 
 96... 
 98... 
 102 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 1 
 
 
 
 2 
 1 
 
 1 
 1 
 
 
 
 
 
 
 
 
 
 1 
 1 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 Total. 
 
 5 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 11 
 
 14 
 
 22 
 
 28 
 
 43 
 
 56 
 
 53 
 
 41 
 
 37 
 
 23 
 
 7 
 
 4 
 
 1 
 
 2 
 
 1 
 
 348 
 
 Mean tibia, 93.69 0.19. S. D. tibia, 5.48 0.14. 
 
 Mean femur, 80.76 0.18. S. D. femur, 5. 19 0.12. r, 0.927 0.005. 
 
 TABLE 30. Correlation coefficients derived from tables 12 to 9. 
 
 Table. 
 
 Characters correlated. 
 
 Coefficient. 
 
 Table. 
 
 Characters correlated. 
 
 Coefficient. 
 
 12 
 
 Ear-length, weight . . . 
 
 0.8360.011 
 
 22 
 
 Femur, skull-length. . 
 
 0.871 0.008 
 
 13 
 
 Ear-length, skull 
 
 
 23 
 
 Tibia, skull-length . . . 
 
 0.806 0.015 
 
 
 length 
 
 0.8360.011 
 
 24 
 
 Femur, humerus 
 
 0.906 0.006 
 
 14 
 
 Ear-length, humerus . 
 
 0.823 0.011 
 
 25 
 
 Femur, humerus(pure 
 
 
 15 
 
 Ear-length, femur. . . . 
 
 0.828 0.011 
 
 
 races only) 
 
 0.980 0.004 
 
 16 
 
 Ear-length, tibia 
 
 0.741 0.016 
 
 26 
 
 Femur, humerus (Fi 
 
 
 17 
 
 Weight, skull-length. . 
 
 0.852 0.010 
 
 
 only) 
 
 0.888 0.017 
 
 18 
 
 Weight, humerus .... 
 
 0.820 0.012 
 
 27 
 
 Femur, humerus (Fi 
 
 
 19 
 
 Weight, femur 
 
 0.8410.011 
 
 28 
 
 only) 
 
 0.878 0.010 
 
 20 
 
 Weight, tibia 
 
 0.758 0.015 
 
 28 
 
 Tibia, humerus 
 
 0.904 0.006 
 
 21 
 
 Humerus, skull-length 
 
 0.834 0.011 
 
 29 
 
 Tibia, femur 
 
 0.927 0.005 
 
 TABLE 31. Number of size factors indicated by each set of measurements as differentiating 
 the three races crossed. 
 
 Race. 
 
 Tibia. 
 
 Femur. 
 
 Humerus. 
 
 Skull- 
 length. 
 
 Weight. 
 
 Ear-length. 
 
 Av. 
 
 Polish-Himalayan . . 
 
 2.1 
 
 2.6 
 
 1.0 
 
 3.1 
 
 1.6 
 
 1.5 
 
 2.0 
 
 Himalayan-Flemish. 
 
 9.8 
 
 7.3 
 
 4.8 
 
 7.0 
 
 9.7 
 
 10.6 
 
 8.2 
 
 Polish-Flemish 
 
 4.7 
 
 5.2 
 
 5.3 
 
 5.6 
 
 21.0 
 
 21.2 
 
 10.5
 
 |J GENETIC STUDIES OF RABBITS AND RATS. 
 
 TABLE 32. Comparative ize of the two sexes in the several groups of cross-bred rabbits. 
 
 Group. 
 
 Tibia. 
 
 Femur. 
 
 Humerus. 
 
 Skull-length. 
 
 Males. 
 
 Females. 
 
 Males. 
 
 Females. 
 
 Males. 
 
 Females. 
 
 Males. 
 
 Females. 
 
 t i 
 
 c 
 
 | 
 
 6 
 
 1 
 
 1 
 
 a 
 
 i 
 
 6 
 y. 
 
 1 
 
 a 
 y. 
 
 i 
 
 
 
 1 
 
 c 
 
 y. 
 
 1 
 
 Fi PXH 
 
 15 93.65 
 24 90.07 
 8100.20 
 33 97.78 
 14 96.59 
 65 94.29 
 
 10 
 :50 
 9 
 88 
 18 
 
 1,2 
 
 91.65 
 89.68 
 97.90 
 96.88 
 95.75 
 92 1 1 
 
 15 
 24 
 
 a 
 
 5:5 
 11 
 
 M 
 
 78.78 
 76.45 
 87.95 
 84.90 
 83.52 
 80.87 
 
 10 
 80 
 9 
 88 
 18 
 
 62 
 
 77.45 
 75.97 
 86.68 
 84.63 
 83.15 
 79.53 
 
 15 
 
 22 
 8 
 53 
 14 
 05 
 
 63.53 
 61.15 
 69.45 
 67.36 
 66.41 
 64.03 
 
 10 
 29 
 9 
 5:5 
 13 
 01 
 
 62.20 
 60.73 
 68.26 
 67.33 
 65.93 
 63.88 
 
 15 
 23 
 
 52 
 11 
 
 15 
 
 70.50 
 69.18 
 79.48 
 76.37 
 75.59 
 73.14 
 
 10 
 
 30 
 
 9 
 
 152 
 13 
 80 
 
 69.95 
 68.80 
 78.58 
 76.66 
 75.50 
 73.12 
 
 F,.PXH 
 
 FI. HXF 
 
 Ft. H XF 
 F,. PXF 
 Ft. PXF 
 
 Weighted mean*. 
 Per cent greater. 
 
 94.72 
 1.58 
 
 93.24 
 
 81.35 
 1.10 
 
 80.46 
 
 64.66 
 0.57 
 
 64.29 
 
 
 73.42 
 0.16 
 
 
 73.30 
 
 
 Anterior 
 skull-width. 
 
 Posterior 
 skull-width. 
 
 Ear-length. 
 
 Weight. 
 
 Group. 
 
 Males. 
 
 Females. 
 
 Males. 
 
 Females. 
 
 Males. 
 
 Females. 
 
 Males. 
 
 Females. 
 
 
 I 
 
 1 
 
 1 
 
 c 
 
 1 
 
 4 
 
 1 
 
 d 
 
 1 
 
 d 
 
 y. 
 
 I 
 
 6 
 
 z 
 
 1 
 
 | 
 
 1 
 
 F,. PXH ] 
 F^PXH S 
 Fi.HXF 
 F,, H XF i 
 F,. PXF 1 
 F,, PXF ( 
 
 5159 90 
 38. 65 
 843.63 
 1141.91 
 442.48 
 (441.28 
 
 10 
 .'51 
 9 
 83 
 13 
 01 
 
 38.65 
 37.94 
 42.36 
 41.38 
 42.13 
 40.32 
 
 15 
 2.'5 
 8 
 51 
 11 
 64 
 
 40.23 
 38.61 
 43.88 
 42.49 
 42.84 
 41.20 
 
 10 
 29 
 1 
 
 33 
 18 
 
 01 
 
 38.35 
 37.90 
 42.70 
 41.50 
 41.58 
 40.38 
 
 15 
 24 
 8 
 
 57 
 14 
 07 
 
 9 
 9 
 
 11 
 11 
 10 
 10 
 
 54 
 .25 
 .45 
 50 
 .91 
 6 
 
 10 
 31 
 9 
 '53 
 13 
 04 
 
 9.42 
 9.16 
 11.66 
 11.65 
 10.97 
 10.71 
 
 15 
 28 
 
 x 
 
 50 
 14 
 il 
 
 1, 
 1. 
 2, 
 2. 
 
 2, 
 2, 
 
 957 
 500 
 094 
 401 
 '.! 
 (WO 
 
 K 
 27 
 8 
 32 
 18 
 
 52 
 
 to to to to -> to 
 
 005 
 704 
 886 
 531 
 545 
 176 
 
 Weighted mean* 
 Per cent greater. 
 
 41.05 
 2.03 
 
 40.23 
 
 41 
 2 
 
 21 
 40 
 
 40.22 
 
 10 
 
 55 
 
 10 
 
 
 .5H 
 .20 
 
 2, 
 
 110 
 
 2, 
 
 221 
 5.26 
 
 The weighted means were obtained by counting each male mean the same number of times 
 as each female mean, the number of individuals assumed for the purpose of the computation 
 to occur in each sex of each gioup being as follows: FI, PXH, 15; F, PXH, 30; Fi, H XF, 10; 
 F,, HXF. 33; F,, PXF. 15; F,. PXF. 66.
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 43 
 
 TABLE 33. Descriptive list of rabbits studied. 
 
 Abbreviations in column headed "color": A, snow-white albino; An, angora; B, black; Dil, 
 dilute; G, gray; H, Himalayan albino; St. G, steel gray; Y, yellow. Measurements in milli- 
 meters; weight in grams. 
 
 I. POLISH, ALL SNOW-WHITE ALBINOS. 
 
 Designation. 
 
 Mother. 
 
 Father. 
 
 Born. 
 
 -3 
 
 MI 
 
 3 
 ja 
 
 CQ 
 
 Anterior skull- 
 width. 
 
 Posterior skull- 
 width. 
 
 3 
 1 
 
 | 
 
 W 
 
 1 
 
 1 
 
 91 
 92 
 99 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 910 
 
 
 
 
 
 
 
 
 
 
 
 
 92413 
 92712 
 92713 
 92738 
 9 2753 
 93186 
 
 1 
 10 
 10 
 2 
 9 
 2738 
 2738 
 2753 
 2753 
 2753 
 
 3 
 3 
 3 
 3 
 3 
 3 
 3 
 3 
 3 
 3 
 
 June 11, 1917 
 Sept. 10, 1917 
 Do. 
 Sept. 13, 1917 
 Sept. 20, 1917 
 June 14, 1918 
 Do. 
 Aug. 16, 1918 
 Do. 
 Do. 
 
 68.9 
 68.4 
 68.2 
 65.5 
 65.4 
 66.2 
 
 63 .6 
 63.6 
 69.3 
 65.0 
 
 65*6 
 67.0 
 63.4 
 65.5 
 67.1 
 64.5 
 64.6 
 
 37.3 
 38.6 
 38.4 
 37.8 
 36.2 
 36.5 
 
 36.5 
 37.5 
 41.0 
 39.6 
 
 39.2 
 37.9 
 38.7 
 38.2 
 36.8 
 38.9 
 38.8 
 
 37.8 
 38.5 
 38.4 
 38.8 
 37.5 
 37.8 
 
 37*8 
 37.4 
 40.5 
 38.4 
 
 38^9 
 37.7 
 38.7 
 38.3 
 37.1 
 37.3 
 39.6 
 
 75.4 
 73.1 
 73.4 
 73.9 
 68.4 
 70.5 
 71.0 
 71.5 
 69.9 
 76.4 
 73.2 
 
 72.5 
 73.0 
 72.9 
 71.0 
 73.3 
 73.6 
 72.8 
 
 8e'4 
 
 84.7 
 86.0 
 84.9 
 80.1 
 80.7 
 81.4 
 84.5 
 79.9 
 89.6 
 84.2 
 
 83.6 
 87.6 
 82.7 
 82.3 
 83.6 
 84.5 
 85.0 
 
 59^3 
 57.1 
 58.8 
 60.3 
 55.5 
 57.0 
 57.3 
 58.2 
 56.7 
 60.9 
 57.5 
 
 57^2 
 58.8 
 57.7 
 57.7 
 57.6 
 57.5 
 58.8 
 
 8.4 
 8.3 
 8.4 
 8.7 
 8.3 
 8.1 
 8.7 
 8.1 
 8.5 
 8.2 
 8.5 
 8.4 
 8.4 
 8.4 
 8.4 
 8.2 
 8.2 
 8.1 
 8.4 
 8.4 
 8.2 
 
 1.275 
 1,425 
 1,545 
 1,575 
 1,250 
 1.355 
 1,295 
 
 1^230 
 1.280 
 1.700 
 1.450 
 
 1^505 
 1,400 
 1.450 
 1.450 
 1,200 
 1,340 
 1.325 
 
 93187 
 93488 
 9 3489 
 93490 
 
 o*3 
 
 0*2312 
 0*2313 
 0*2314 
 o"2412 
 0*2741 
 0*2742 
 0*2751 
 0*3318 
 o"3487 
 0*3561 
 
 10 
 10 
 10 
 
 1 
 2 
 2 
 9 
 2713 
 2753 
 2712 
 
 3 
 3 
 3 
 3 
 3 
 3 
 3 
 3 
 3 
 3 
 
 May 28, 1917 
 Do. 
 Do. 
 June 11, 1917 
 Sept. 13, 1917 
 Do. 
 Sept. 20, 1917 
 June 17, 1918 
 Aug. 16, 1918 
 Aug. 21, 1918 
 
 II. HIMALAYAN, ALL "HIMALAYAN" ALBINOS. 
 
 
 
 
 
 i 
 
 "5 
 
 .M 
 
 ]j 
 
 
 
 
 
 
 Designation. 
 
 1 
 
 | 
 
 Born. 
 
 I 
 
 l| 
 
 ll 
 
 s 
 
 S 
 
 1 
 
 I 
 
 
 > 
 
 
 1 
 
 1 
 
 
 i 
 
 < * 
 
 * 
 
 
 B 
 
 = 
 
 
 
 i 
 
 94 
 
 
 
 
 66 1 
 
 35 8 
 
 37 3 
 
 77.3 
 
 92.9 
 
 61 .". 
 
 
 
 96 
 
 
 
 
 72.9 
 
 39.6 
 
 40.2 
 
 K2.S 
 
 95.9 
 
 63.9 
 
 9.7 
 
 2.210 
 
 92206 
 
 4 
 
 5 
 
 Apr. 27, 1917 
 
 69.1]37.3 
 
 37.4 
 
 79.3 
 
 94.3 
 
 62.4 
 
 9.2 
 
 2,085 
 
 92210 
 
 4 
 
 5 
 
 Do. 
 
 69.0137.3 
 
 38.0 
 
 80.7 
 
 94.8 
 
 63.8 
 
 9.5 
 
 1,835 
 
 9 3565 
 
 2210 
 
 2208 
 
 Aug. 21, 1918 67.5|35.9 
 
 37.4 
 
 77.8 
 
 92.1 
 
 63.9 
 
 9.5 
 
 1,620 
 
 93566 
 
 2210 
 
 2208 
 
 Do. 66.9135.3 
 
 . 72 1 37 3 
 
 37.1 
 37 4 
 
 77.0 
 81.3 
 
 92.9 
 96.0 
 
 62.8 
 ft? 9 
 
 9.6 
 
 1,600 
 
 c?2208 
 
 4 
 
 5 
 
 Apr. 27.1917 69.138.2 
 
 39.2 
 
 80.0 
 
 93.0163.6 
 
 9.4 
 
 1.850 
 
 
 
 
 1 ] 
 
 
 | 
 

 
 44 
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 TABLE 33. Descriptive list of rabbits studied Continued. 
 III. FLIMIBH GIANT. 
 
 Designa- 
 tion. 
 
 , 
 
 | 
 
 j 
 
 Born. 
 
 1 
 
 Anterior skull- 
 width. 
 
 Posterior skull- 
 width. 
 
 
 
 1 
 
 H 
 
 1 
 
 1 
 
 9B 
 97 
 cfA 
 <72 
 c?2681 
 
 B 
 
 StG 
 StG 
 StG 
 StG 
 
 
 
 
 82.9 
 87.1 
 88.2 
 84.6 
 85.6 
 
 44.5 
 45.4 
 46.7 
 43.8 
 47.4 
 
 44.7 
 44.0 
 47.4 
 44.9 
 46.4 
 
 95.3 
 97.8 
 102.6 
 94.1 
 98.5 
 
 106.7 
 113.1 
 116.4 
 105.2 
 113.5 
 
 73.1 
 75.6 
 
 73^4 
 77.9 
 
 
 
 
 
 
 14.7 
 
 14'e 
 14.3 
 
 4,060 
 
 3^480 
 3,400 
 
 
 
 
 
 
 'Sept."8.'l917 
 
 9B 
 
 rf2 
 
 IV. Fi, POLISH X HIMALAYAN, ALL "HIMALAYAN" ALBINOS. 
 
 Designation. 
 
 Mother. 
 
 1 
 1 
 
 Born. 
 
 Skull-length 
 
 Anterior skull- 
 width. 
 
 Posterior skull- 
 width. 
 
 j 
 
 .2 
 
 .0 
 
 W 
 
 1 
 
 1 
 
 92317 
 92320 
 
 9P 
 9P 
 4H 
 2P 
 2P 
 6H 
 10P 
 2206 H 
 2210 H 
 2210H 
 9P 
 9P 
 9P 
 4H 
 4H 
 4H 
 2P 
 2P 
 2P 
 6H 
 6H 
 6H 
 6H 
 6H 
 2210H 
 
 5H 
 5H 
 3P 
 5H 
 5H 
 3P 
 5H 
 3P 
 3P 
 3P 
 5H 
 5H 
 5H 
 3P 
 3P 
 3P 
 5H 
 5H 
 5H 
 3P 
 3P 
 3P 
 3P 
 3P 
 3P 
 
 May 28, 1917 
 Do. 
 Do. 
 May 29, 1917 
 Do. 
 June 4,1917 
 June 28, 1917 
 Apr. 27, 1918 
 Do. 
 Do. 
 May 28, 1917 
 Do. 
 Do. 
 May 28, 1917 
 Do. 
 Do. 
 May 29, 1917 
 Do. 
 Do. 
 June 4, 1917 
 Do. 
 Do. 
 Do. 
 Do. 
 Apr. 27, 1918 
 
 74.8 
 72.3 
 70.5 
 70.5 
 70.8 
 68.7 
 70.7 
 62.1 
 67.8 
 71.4 
 74.5 
 70.4 
 72.7 
 69.0 
 71.0 
 71.7 
 68.1 
 68.5 
 70 9 
 68.5 
 71.3 
 70.6 
 70.8 
 70.7 
 68.4 
 
 39.9 
 39.6 
 38.7 
 38.8 
 39.8 
 38.5 
 38.7 
 37.0 
 36.9 
 38.8 
 41.0 
 39.0 
 40.2 
 39.4 
 40.7 
 40.9 
 39.4 
 38.9 
 40 4 
 41.8 
 40.9 
 39.3 
 39.9 
 40.6 
 38.4 
 
 38.6 
 38.5 
 38.5 
 39.4 
 39.6 
 38.2 
 36.8 
 37.3 
 37.5 
 38.7 
 40.2 
 38.8 
 40.0 
 39.6 
 40.9 
 40.6 
 40.2 
 37.8 
 40 5 
 42.7 
 41.4 
 39.4 
 40.7 
 41.0 
 39.9 
 
 79.0 
 78.6 
 79.0 
 76.9 
 77.8 
 78.5 
 78.4 
 73.9 
 75.4 
 77.9 
 79.9 
 78.4 
 78.0 
 77.9 
 79.7 
 82.0 
 76.5 
 75.5 
 77.3 
 78.9 
 81.9 
 78.7 
 80.5 
 80.7 
 77.4 
 
 95.4 
 93.2 
 93.7 
 91.7 
 92.7 
 91.9 
 91.5 
 86.0 
 89.2 
 91.8 
 96.5 
 92.9 
 93.4 
 93.9 
 96.8 
 96.8 
 91.2 
 90.3 
 92.7 
 91.7 
 96.8 
 92.9 
 94.0 
 95.5 
 91.6 
 
 64.7 
 63.3 
 63.7 
 62.2 
 63.0 
 62.5 
 61.6 
 59.3 
 60.7 
 60.9 
 64.6 
 63.0 
 62.8 
 62.6 
 63.7 
 65.1 
 62.7 
 61.9 
 62.4 
 62.4 
 64.5 
 62.6 
 63.7 
 63 8 
 62.8 
 
 9.6 
 9.4 
 9.6 
 9.5 
 9.7 
 9.5 
 9.2 
 
 9.4 
 9.3 
 9.7 
 9.5 
 9.3 
 9.5 
 9.5 
 9.7 
 9.4 
 9.4 
 98 
 9.4 
 9.7 
 9.6 
 9.5 
 9.5 
 9.6 
 
 2,270 
 2,285 
 1,940 
 2,390 
 2.495 
 1,940 
 1.675 
 
 l!540 
 1,825 
 2,145 
 1.945 
 1,770 
 1.835 
 1,920 
 2.060 
 1,945 
 1.945 
 2,110 
 2,175 
 2,045 
 1.865 
 1.870 
 2,000 
 1.735 
 
 9 2323 
 
 92340 . 
 
 92341 
 
 92395 
 92446 
 
 93094 
 
 93099 
 93100 
 c?2316 
 d"2318 
 d"2319 
 d"2321 
 d"2322 
 d"2324 
 c?2342 
 d"2343 
 d"2344 
 c?2391 
 tf2392 
 
 cf2393 
 d"2394 
 
 rf2396 
 d*3101 

 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 45 
 
 TABLE 33. Descriptive list of rabbits studied Continued. 
 V. Fi, POLISH X FLEMISH. 
 
 Designa- 
 tion. 
 
 Color. 
 
 1 
 
 1 
 
 Born. 
 
 C3 
 
 -2 
 
 "3 
 QQ 
 
 terior skull- 
 dth" 
 
 
 <e 
 
 I 
 
 
 i 
 
 
 
 o 
 
 1 
 
 
 1 
 
 02 
 
 1? 
 
 " 
 
 (2 
 
 ' 
 
 K 
 
 1 
 
 I 
 
 92430 
 
 G 
 
 7F 
 
 3P 
 
 June 29, 1917 
 
 74.6 
 
 42.8 
 
 41.8 
 
 86.2 
 
 99.1 
 
 66.0 
 
 11.1 
 
 2,680 
 
 92431 
 
 StG 
 
 7F 
 
 3P 
 
 Do. 
 
 74.7 
 
 41.8 
 
 42.7 
 
 81.8 
 
 92.1 
 
 64.9 
 
 11.2 
 
 2.500 
 
 92432 
 
 B 
 
 7F 
 
 3P 
 
 Do. 
 
 77.0 
 
 42.3 
 
 42.8 
 
 83.3 
 
 96.8 
 
 65.0 
 
 11.2 
 
 2.500 
 
 92436 
 
 G 
 
 7F 
 
 3P 
 
 Do. 
 
 74.3 
 
 42.1 
 
 40.5 
 
 84.1 
 
 98.5 
 
 65.8 
 
 10.3 
 
 2,300 
 
 92437 
 
 G 
 
 7F 
 
 3P 
 
 Do. 
 
 76.3 
 
 42.4 
 
 41.8 
 
 83.7 
 
 96.8 
 
 65.0 
 
 11.0 
 
 2.500 
 
 92451 
 
 G 
 
 9P 
 
 2F 
 
 July 7, 1917 
 
 76.3 
 
 42.8 
 
 41.5 
 
 83.3 
 
 96.8 
 
 67.9 
 
 11.0 
 
 2,300 
 
 92474 
 
 B 
 
 BF 
 
 3P 
 
 July 8, 1917 
 
 74.5 
 
 40.0 
 
 39.7 
 
 83.7 
 
 95.9 
 
 66.6 
 
 11.3 
 
 2.055 
 
 92507 
 
 StG 
 
 2P 
 
 2F 
 
 July 19, 1917 
 
 75.3 
 
 42.4 
 
 41.7 
 
 81.7 
 
 93.7 
 
 65.8 
 
 11.1 
 
 2.730 
 
 92508 
 
 StG 
 
 2P 
 
 2F 
 
 Do. 
 
 74.4 
 
 41.6 
 
 42.3 
 
 81.5 
 
 94.0 
 
 65.4 
 
 11.3 
 
 2,715 
 
 92509 
 
 StG 
 
 2P 
 
 2F 
 
 Do. 
 
 76.0 
 
 42.0 
 
 40.9 
 
 82.8 
 
 97.0 
 
 65.3 
 
 11.1 
 
 2,545 
 
 92510 
 
 StG 
 
 2P 
 
 2F 
 
 Do. 
 
 75.7 
 
 43.2 
 
 42.3 
 
 82.9 
 
 94.4 
 
 66.8 
 
 10.8 
 
 2,890 
 
 92511 
 
 StG 
 
 2P 
 
 2F 
 
 Do. 
 
 76.3 
 
 41.9 
 
 41.4 
 
 82.3 
 
 93.7 
 
 66.8 
 
 10.9 
 
 2,660 
 
 92576 
 
 G 
 
 IP 
 
 2F 
 
 July 26, 1917 
 
 76.2 
 
 42.8 
 
 41.7 
 
 84.0 
 
 96.0 
 
 66.4 
 
 10.3 
 
 2,720 
 
 c?2429 
 
 G 
 
 7F 
 
 3P 
 
 June 29, 1917 
 
 74.7 
 
 41.2 
 
 41.5 
 
 81.8 
 
 96.2 
 
 63.7 
 
 10.3 
 
 2,385 
 
 0*2433 
 
 StG 
 
 7F 
 
 3P 
 
 Do. 
 
 76.9 
 
 43.7 
 
 43.9 
 
 85.4 
 
 99.9 
 
 67.5 
 
 11.0 
 
 2.735 
 
 0^2434 
 
 B 
 
 7F 
 
 3P 
 
 Do. 
 
 76.2 
 
 41.8 
 
 43.0 
 
 84.9 
 
 98.7 
 
 66.7 
 
 10.8 
 
 2.525 
 
 0^2435 
 
 G 
 
 7F 
 
 3P 
 
 Do. 
 
 74.3 
 
 42.5 
 
 42.8 
 
 85.8 
 
 100.2 
 
 67.0 
 
 10.6 
 
 2.526 
 
 0*2454 
 
 StG 
 
 9P 
 
 2F 
 
 July 7, 1917 
 
 75.8 
 
 41.7 
 
 42.6 
 
 84.8 
 
 100.5 
 
 67.3 
 
 11.6 
 
 2,380 
 
 0*2473 
 
 B 
 
 BF 
 
 3P 
 
 July 8, 1917 
 
 79.8 
 
 44.4 
 
 44.4 
 
 86.7 
 
 98.7 
 
 68.5 
 
 11.4 
 
 2.670 
 
 cf2506 
 
 StG 
 
 2P 
 
 2F 
 
 July 19, 1917 
 
 73.8 
 
 42.6 
 
 43.0 
 
 80.1 
 
 92.7 
 
 64.1 
 
 10.3 
 
 2,350 
 
 0"2577 
 
 StG 
 
 IP 
 
 2F 
 
 July 26, 1917 
 
 77.2 
 
 42.2 
 
 41.9 
 
 84.0 
 
 96.2 
 
 66.8 
 
 11.0 
 
 2,500 
 
 0*2578 
 
 StG 
 
 IP 
 
 2F 
 
 Do. 
 
 73.0 
 
 42.3 
 
 42.0 
 
 82.1 
 
 94.5 
 
 64.4 
 
 10.3 
 
 2,160 
 
 0*2650 
 
 G 
 
 9P 
 
 2F 
 
 Aug. 9,1917 
 
 75.5 
 
 42.7 
 
 42.8 
 
 82.0 
 
 95.4 
 
 65.5 
 
 11.0 
 
 2,500 
 
 0*2834 
 
 G 
 
 10P 
 
 2F 
 
 Dec. 7, 1917 
 
 75.9 
 
 43.1 
 
 42.6 
 
 85.2 
 
 96.2 
 
 67.1 
 
 10.7 
 
 2,445 
 
 0*2865 
 
 G 
 
 2P 
 
 2F 
 
 Dec. 9, 1917 
 
 75.5 
 
 42.8 
 
 44.1 
 
 83.9 
 
 94.7 
 
 67.8 
 
 11.4 
 
 2,400 
 
 CJ*2866 
 
 G 
 
 2P 
 
 2F 
 
 Do. 
 
 75.0 
 
 41.8 
 
 42.5 
 
 82.8 
 
 95.3 
 
 66.7 
 
 11.4 
 
 2.650 
 
 0*2867 
 
 StG 
 
 2P 
 
 2F 
 
 Do. 
 
 74.6 
 
 42.0 
 
 42.1 
 
 80.7 
 
 93.2 
 
 66.1 
 
 10.9 
 
 2.350 
 
 VI. Fi, HIMALAYAN XFLEMISH. 
 
 
 
 
 
 
 f' 
 
 | 
 
 | 
 
 
 
 
 
 
 Designa- 
 tion. 
 
 Color. 
 
 1 
 
 1 
 
 Born. 
 
 
 
 3 
 
 11 
 
 S -o 
 
 1 
 
 i 
 
 1 
 
 
 i 
 
 
 
 S 
 
 i 
 
 
 a 
 
 <! 
 
 & * 
 
 t 
 
 P 
 
 1 
 
 W 
 
 * 
 
 92517 
 
 StG 
 
 4H 
 
 2F 
 
 July 19.1917 
 
 76.4 
 
 42.4 
 
 42.9 
 
 86.6 
 
 99.8 
 
 69.3 
 
 11.8 
 
 3,040 
 
 92519 
 
 G 
 
 4H 
 
 2F 
 
 Do. 
 
 78.7 
 
 42.8 
 
 43.4 
 
 85.1 
 
 97.5 
 
 67.0 
 
 11.8 
 
 2.800 
 
 92521 
 
 G 
 
 4H 
 
 2F 
 
 Do. 
 
 80.0 
 
 43.1 
 
 42.1 
 
 88.4 
 
 102.1 
 
 71.1 
 
 11.5 
 
 3,060 
 
 92642 
 
 StG 
 
 6H 
 
 2F 
 
 Aug. 9, 1917 
 
 79.5 
 
 42.8 
 
 43.5 
 
 88.7 
 
 99.7 
 
 69.0 
 
 11.8 
 
 2,800 
 
 92645 
 
 StG 
 
 6H 
 
 2F 
 
 Do. 
 
 78.8 
 
 43.5 
 
 42.7 
 
 86.5 
 
 96.8 
 
 67.0 
 
 11.8 
 
 2,800 
 
 92646 
 
 G 
 
 6H 
 
 2F 
 
 Do. 
 
 81.5 
 
 43.4 
 
 43.2 
 
 86.2 
 
 97.2 
 
 67.8 
 
 11.6 
 
 2,765 
 
 92828 
 
 StG 
 
 6H 
 
 2F 
 
 Dec. 7, 1917 
 
 76.3 
 
 41.8 
 
 40.9 
 
 84.8 
 
 95.0 
 
 66.2 
 
 11.3 
 
 2,775 
 
 92830 
 
 G 
 
 6H 
 
 2F 
 
 Do. 
 
 79.9 
 
 42.3 
 
 43.7 
 
 88.7 
 
 97.8 
 
 68.411.9 
 
 3,050 
 
 92832 
 
 StG 
 
 6H 
 
 2F 
 
 Do. 
 
 76.3 
 
 39.7 
 
 42.0 
 
 85.0 
 
 95.5 
 
 68 3 
 
 11.5 
 
 
 0*2518 
 
 G 
 
 4H 
 
 2F 
 
 July 19, 1917 
 
 78.6 
 
 42.3 
 
 43.1 
 
 88.1 
 
 99.9 
 
 71.011.3 
 
 2^440 
 
 0*2520 
 
 StG 
 
 4H 
 
 2F 
 
 Do. 
 
 77.6 
 
 43.8 
 
 44.2 
 
 86.8 
 
 100.9 
 
 69.1 
 
 11.5 
 
 2.775 
 
 0*2522 
 
 G 
 
 4H 
 
 2F 
 
 Do. 
 
 79.6 
 
 44.6 
 
 44.1 
 
 88.4 
 
 101.0 
 
 69.4 
 
 11.7 
 
 2.875 
 
 0*2643 
 
 StG 
 
 6H 
 
 2F 
 
 Aug. 9, 1917 
 
 82.8 
 
 46.3 
 
 44.4 
 
 91.9 
 
 105.0 
 
 70.9 
 
 11.4 
 
 2.900 
 
 0*2644 
 
 StG 
 
 6H 
 
 2F 
 
 Do. 
 
 79.3 
 
 41.7 
 
 43.9 
 
 86.2 
 
 98.1 
 
 68.8 
 
 11.4 
 
 2.550 
 
 0*2647 
 
 G 
 
 6H 
 
 2F 
 
 Do. 
 
 80.4 
 
 43.2 
 
 44.0 
 
 88.2 
 
 99.0 
 
 68.611.7 
 
 2.600 
 
 0*2648 
 
 G 
 
 6H 
 
 2F 
 
 Do. 
 
 
 44.5 
 
 44.6 
 
 87.4 
 
 98.6 
 
 68 711.4 
 
 2.665 
 
 0*2649 
 
 G 
 
 6H 
 
 2F 
 
 Do. 
 
 78^2 
 
 42.7 
 
 43.0 
 
 86.8 
 
 98.9 
 
 69.311.2 
 
 2.750
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 TABLE 33. Descriptive litt of rabbits studied Continued. 
 
 VII. Fj, POLISH XHlMALAYAN. 
 
 Decn- 
 
 tion. 
 
 Color. 
 
 j 
 
 j 
 
 Born. 
 
 Skull-length. 
 
 Anterior skull- 
 width. 
 
 1 Posterior skull- 
 width. 
 
 1 
 
 t 
 
 K 
 
 1 
 
 * 
 
 1 
 
 92915 
 
 H 
 
 2323 
 
 2324 
 
 Apr. 16, 1918 
 
 68.9 
 
 38.1 
 
 38.4 
 
 77.7 
 
 90.7 
 
 61.5 
 
 9.5 
 
 1.880 
 
 92916 
 
 A 
 
 2323 
 
 2324 
 
 Do. 
 
 65.6 
 
 35.5 
 
 36.5 
 
 74.6 
 
 87.6 
 
 58.5 
 
 9.1 
 
 1.230 
 
 92993 
 
 H 
 
 2446 
 
 2342 
 
 Apr. 18, 1918 
 
 65.3 
 
 36.4 
 
 
 74.4 
 
 87.4 
 
 60.6 
 
 8.8 
 
 
 93028 
 
 A 
 
 2320 
 
 2316 
 
 Apr. 21, 1918 
 
 75.0 
 
 39.5 
 
 38!7 
 
 80.2 
 
 96.2 
 
 63.9 
 
 9.5 
 
 1.800 
 
 93029 
 
 A 
 
 2320 
 
 2316 
 
 Do. 
 
 69.1 
 
 37.8 
 
 37.5 
 
 75.7 
 
 91.4 
 
 61.2 
 
 9.2 
 
 1.515 
 
 93173 
 
 H 
 
 2320 
 
 2316 
 
 June 14. 1918 
 
 70.3 
 
 . p ! 
 
 35.7 
 
 78.7 
 
 91.4 
 
 62.1 
 
 9.5 
 
 1.490 
 
 93426 
 
 H 
 
 2317 
 
 2316 
 
 July 4, 1918 
 
 72.6 
 
 36.5 
 
 36.9 
 
 77.8 
 
 91.0 
 
 62.1 
 
 9.5 
 
 1.425 
 
 93427 
 
 H 
 
 2317 
 
 2316 
 
 Do. 
 
 67.7 
 
 36.9 
 
 37.0 
 
 76.7 
 
 91.0 
 
 62.0 
 
 9.2 
 
 
 93428 
 
 H 
 
 2317 
 
 2316 
 
 Do. 
 
 72.5 
 
 38.4 
 
 37.8 
 
 76.6 
 
 90.7 
 
 61.5 
 
 9.1 
 
 1.685 
 
 93544 
 
 A 
 
 2323 
 
 2324 
 
 Aug. 15, 1918 
 
 70.4 
 
 39.2 
 
 39.5 
 
 79.3 
 
 92.7 
 
 64.5 
 
 9.5 
 
 1.700 
 
 93545 
 
 A 
 
 2323 
 
 2324 
 
 Do. 
 
 70.1 
 
 40.0 
 
 :w ( 
 
 80.5 
 
 94.3 
 
 64.9 
 
 9.7 
 
 1,980 
 
 93610 
 
 H 
 
 2446 
 
 2316 
 
 Sept. 1, 1918 
 
 69.6 
 
 36.9 
 
 36.9 
 
 75.7 
 
 89.0 
 
 60.8 
 
 8.8 
 
 1.750 
 
 93611 
 
 H 
 
 2446 
 
 2316 
 
 Do. 
 
 65.3 
 
 37.3 
 
 37.3 
 
 73.3 
 
 86.4 
 
 58 . : 
 
 8.5 
 
 
 93629 
 
 H (Blue) 
 
 2320 
 
 2344 
 
 Nov. 2, 1918 
 
 71.6 
 
 40.5 
 
 39.2 
 
 77.8 
 
 92.7 
 
 61.5 
 
 8.9 
 
 2^170 
 
 93633 
 
 H (Blue) 
 
 2320 
 
 2344 
 
 Do. 
 
 67.2 
 
 37.4 
 
 37.8 
 
 76.7 
 
 92.7 
 
 62.4 
 
 9.1 
 
 1.705 
 
 93634 
 
 A 
 
 2320 
 
 2344 
 
 Do. 
 
 70.6 
 
 39.6 
 
 39.3 
 
 76.9 
 
 91.4 
 
 63.1 
 
 9.2 
 
 1.715 
 
 93637 
 
 H (Blue) 
 
 2317 
 
 2344 
 
 Do. 
 
 69.1 
 
 39.9 
 
 39.4 
 
 78.7 
 
 92.7 
 
 63.7 
 
 9.9 
 
 2,325 
 
 93638 
 
 H 
 
 2317 
 
 2344 
 
 Do. 
 
 70.4 
 
 36.8 
 
 37.1 
 
 77.7 
 
 92.8 
 
 62.4 
 
 9.1 
 
 1.900 
 
 93641 
 
 A 
 
 2317 
 
 2344 
 
 Do. 
 
 
 
 
 
 
 
 8.9 
 
 
 94079 
 
 H 
 
 2323 
 
 2324 
 
 Apr. 3, 1919 
 
 67^2 
 
 38^5 
 
 37.6 
 
 76~9 
 
 89^4 
 
 60.5 
 
 9.8 
 
 1.466 
 
 94193 
 
 H 
 
 3094 
 
 2324 
 
 May 26, 1919 
 
 70.2 
 
 39.7 
 
 38.1 
 
 77.2 
 
 90.6 
 
 61.8 
 
 9.8 
 
 1.985 
 
 94194 
 
 A 
 
 3094 
 
 2324 
 
 Do. 
 
 69.6 
 
 38.9 
 
 as. 6 
 
 77.3 
 
 89.8 
 
 61.9 
 
 9.2 
 
 1.810 
 
 94196 
 
 H 
 
 3099 
 
 2324 
 
 Do. 
 
 68.8 
 
 39.3 
 
 38.5 
 
 77.5 
 
 90.9 
 
 
 9.8 
 
 1,615 
 
 94201 
 
 A 
 
 2320 
 
 2344 
 
 June 3, 1919 
 
 66.0 
 
 36.5 
 
 37.3 
 
 68.4 
 
 80.4 
 
 54.6 
 
 8.3 
 
 1,520 
 
 94202 
 
 A 
 
 2320 
 
 2344 
 
 Do. 
 
 68.9 
 
 38.4 
 
 39.3 
 
 73.4 
 
 86.5 
 
 57.6 
 
 9.0 
 
 1,865 
 
 94204 
 
 H 
 
 2320 
 
 2344 
 
 Do. 
 
 65.5 
 
 37.9 
 
 37.3 
 
 73.0 
 
 85.8 
 
 58.3 
 
 8.7 
 
 1,600 
 
 94205 
 
 H 
 
 2320 
 
 2344 
 
 Do. 
 
 65.9 
 
 36.0 
 
 36.6 
 
 74.1 
 
 88.0 
 
 56.5 
 
 8.8 
 
 1,620 
 
 94207 
 
 H 
 
 2320 
 
 2344 
 
 Do. 
 
 68.2 
 
 37.5 
 
 38.8 
 
 74.3 
 
 86.4 
 
 59.5 
 
 9.2 
 
 1.825 
 
 94208 
 
 H 
 
 2320 
 
 2344 
 
 Do. 
 
 67.2 
 
 38.1 
 
 37.7 
 
 69.8 
 
 82.3 
 
 54.9 
 
 8.9 
 
 1.530 
 
 94270 
 
 H 
 
 2323 
 
 2324 
 
 July 25, 1919 
 
 65.4 
 
 37.2 
 
 37.1 
 
 75.0 
 
 89.4 
 
 60.2 
 
 8.7 
 
 1.300 
 
 94333 
 
 A 
 
 2446 
 
 2344 
 
 July 26, 1919 
 
 69.5 
 
 37.9 
 
 37.8 
 
 75.6 
 
 89.5 
 
 59.5 
 
 8.8 
 
 1.600 
 
 c?3170 
 
 H 
 
 2320 
 
 2316 
 
 June 14, 1918 
 
 68.8 
 
 37.5 
 
 36.7 
 
 74.8 
 
 88.2 
 
 60.4 
 
 9.7 
 
 1,340 
 
 (73171 
 
 H 
 
 2320 
 
 2316 
 
 Do. 
 
 68.8 
 
 38.0 
 
 38.2 
 
 76.0 
 
 89.4 
 
 60.3 
 
 8.9 
 
 1,395 
 
 <f3172 
 
 H 
 
 2320 
 
 2316 
 
 Do. 
 
 
 
 
 78.2 
 
 88.0 
 
 
 9.4 
 
 
 d"3231 
 
 H 
 
 2395 
 
 2324 
 
 Do. 
 
 68^9 
 
 38.5 
 
 38.9 
 
 74.6 
 
 86.3 
 
 59.8 
 
 9.2 
 
 1.505 
 
 tf3429 
 
 H 
 
 2317 
 
 2316 
 
 July 4, 1918 
 
 71.7 
 
 40.0 
 
 39.5 
 
 77.0 
 
 92.0 
 
 62.3 
 
 9.5 
 
 1.655 
 
 C73642 
 
 A 
 
 2323 
 
 2324 
 
 Aug. 15, 1918 
 
 66.1 
 
 38.7 
 
 38.9 
 
 76.6 
 
 90.6 
 
 60.2 
 
 9.0 
 
 1,630 
 
 0"3643 
 
 H 
 
 2323 
 
 2324 
 
 Do. 
 
 69.6 
 
 39.8 
 
 40.0 
 
 79.6 
 
 94.6 
 
 63.6 
 
 9.4 
 
 1.620 
 
 <f3609 
 
 H 
 
 2446 
 
 2316 
 
 Sept. 1, 1918 
 
 71.1 
 
 40.0 
 
 39.7 
 
 78 
 
 90.4 
 
 61.7 
 
 9.3 
 
 1.910 
 
 rf3630 
 
 A 
 
 2320 
 
 2344 
 
 Nov. 2, 1918 
 
 71.5 
 
 38.5 
 
 38.2 
 
 80.1 
 
 94.3 
 
 63.9 
 
 9.4 
 
 1.820 
 
 <f3632 
 
 H 
 
 2320 
 
 2344 
 
 Do. 
 
 70.9 
 
 39.2 
 
 38.9 
 
 78.6 
 
 94.2 
 
 63.2 
 
 9.3 
 
 1.770 
 
 d<3636 
 
 H 
 
 2317 
 
 2344 
 
 Do. 
 
 67.6 
 
 37.4 
 
 37.3 
 
 77.0 
 
 93.5 
 
 62.9 
 
 9.2 
 
 1.410 
 
 <f303G 
 
 H 
 
 2317 
 
 2344 
 
 Do. 
 
 70.8 
 
 39.5 
 
 W.4 
 
 77.8 
 
 93.5 
 
 63.7 
 
 9.2 
 
 1,585 
 
 <f3639 
 
 H 
 
 2317 
 
 2344 
 
 Do. 
 
 71.6 
 
 39.7 
 
 38.8 
 
 78.4 
 
 94.1 
 
 63.8 
 
 9.7 
 
 1.720 
 
 (73640 
 
 A 
 
 2317 
 
 2344 
 
 Do. 
 
 72.0 
 
 40.5 
 
 40.4 
 
 78.6 
 
 93.4 
 
 63.7 
 
 9.4 
 
 ,890 
 
 (74196 
 
 B 
 
 3094 
 
 2324 
 
 May 26, 1919 
 
 67.3 
 
 36.9 
 
 5.9 
 
 73.5 
 
 86.9 
 
 58.7 
 
 9.1 
 
 .390 
 
 (74199 
 
 H 
 
 3099 
 
 2324 
 
 Do. 
 
 69.0 
 
 38.6 
 
 7.4 
 
 76.6 
 
 90.6 
 
 62.4 
 
 8.9 
 
 ,375 
 
 (74203 
 
 A 
 
 2320 
 
 2344 
 
 June 3, 1919 
 
 67.6 
 
 38.9 
 
 8.6 
 
 73.3 
 
 85.7 
 
 58.2 
 
 9.3 
 
 .610 
 
 c'41'Wi 
 
 H 
 
 2320 
 
 2344 
 
 Do. 
 
 68.2 
 
 40.2 
 
 9.6 
 
 72.3 
 
 83.7 
 
 56.7 
 
 9.5 
 
 ,600 
 
 (74209 
 
 H 
 
 2320 
 
 2344 
 
 Do. 
 
 68.3 
 
 so 
 
 8.7 
 
 73.7 
 
 86.6 
 
 58.2 
 
 9.3 
 
 ,435 
 
 cTOU 
 
 H (Blue) 
 
 2323 
 
 2324 
 
 July 25, 1919 
 
 68.8 
 
 9.4 
 
 8.4 
 
 78.8 
 
 91.5 
 
 
 9.0 
 
 ,510 
 
 MM 
 
 A 
 
 2323 
 
 2324 
 
 Do. 
 
 71.1 
 
 9.2 
 
 00 
 
 78.7 
 
 94.2 
 
 62^6 
 
 9.7 
 
 ,500 
 
 u'4l!9 
 
 H 
 
 2323 
 
 2324 
 
 Do. 
 
 65.0 
 
 6.3 
 
 6.0 
 
 73.1 
 
 84.9 
 
 60.8 
 
 8.4 
 
 ,090 
 
 (74332 
 
 A 
 
 2446 
 
 2344 
 
 June 26, 1919 
 
 67.9 
 
 6.8 
 
 6.4 
 
 74.0 
 
 86.8 
 
 59.8 
 
 8.9 
 
 ,400 
 
 (74334 
 
 A 
 
 2446 
 
 2344 
 
 Do. 
 
 69.0 
 
 B.I 
 
 83 
 
 75.3 
 
 88.8 
 
 9.5 
 
 9.3 
 
 ,715
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 47 
 
 TABLE 33. Descriptive list of rabbits studied Continued. 
 VIII. Fj, POLISH XFLEMISH. 
 
 Designa- 
 tion. 
 
 Color. 
 
 i 
 
 
 
 Born. 
 
 Skull-length. 
 
 Sj 
 
 11 
 3* 
 
 Posterior skull- 1 
 width. 
 
 
 
 05 
 
 a 
 
 S 
 
 Humerus. 
 
 1 
 
 Weight. 
 
 92908 
 
 A 
 
 2436 
 
 2434 
 
 Apr. 16, 1918 
 
 76.3 
 
 41.7 
 
 39.6 
 
 K3.4 
 
 95.5 
 
 63.7 
 
 10 
 
 2,060 
 
 92909 
 
 Y 
 
 2436 
 
 2434 
 
 Do. 
 
 
 
 
 
 
 
 10.4 
 
 
 92918 
 
 B 
 
 2509 
 
 2506 
 
 Apr. 17. 1918 
 
 71.6 
 
 41.6 
 
 41^6 
 
 80^3 
 
 92.8 
 
 63^8 
 
 11.1 
 
 2^490 
 
 92920 
 
 StG 
 
 2509 
 
 2506 
 
 Do. 
 
 70.5 
 
 39.5 
 
 40.2 
 
 80.0 
 
 93.7 
 
 64.8 
 
 11.3 
 
 
 92929 
 
 StG 
 
 2451 
 
 2506 
 
 Do. 
 
 72.8 
 
 41.5 
 
 40.8 
 
 K0.3 
 
 91.6 
 
 64.6 
 
 10.7 
 
 2^400 
 
 92932 
 
 A 
 
 2451 
 
 2506 
 
 Do. 
 
 73.3 
 
 40.3 
 
 40.2 
 
 79.3 
 
 92.5 
 
 65.3 
 
 10.5 
 
 2.430 
 
 92943 
 
 B An 
 
 2430 
 
 2434 
 
 Do. 
 
 75.6 
 
 40.5 
 
 38.6 
 
 82.3 
 
 96.8 
 
 65.3 
 
 11.6 
 
 2,150 
 
 93002 
 
 B 
 
 2576 
 
 2506 
 
 Apr. 19, 1918 
 
 74.5 
 
 41.7 
 
 41.7 
 
 83.2 
 
 95.2 
 
 66.4 
 
 11.9 
 
 
 93004 
 
 A 
 
 2576 
 
 2506 
 
 Do. 
 
 73.0 
 
 40.9 
 
 39.8 
 
 79.0 
 
 91.8 
 
 64.0 
 
 9.8 
 
 2,055 
 
 93008 
 
 StG 
 
 2510 
 
 2506 
 
 Do. 
 
 73.0 
 
 40.0 
 
 38.7 
 
 79.6 
 
 90.7 
 
 63.2 
 
 10.8 
 
 
 93009 
 
 G 
 
 2510 
 
 2506 
 
 Do. 
 
 67.9 
 
 39.5 
 
 39.7 
 
 77.7 
 
 90.2 
 
 63.3 
 
 10.3 
 
 
 93010 
 
 Blue G 
 
 2510 
 
 2506 
 
 Do. 
 
 73.5 
 
 41.6 
 
 40.7 
 
 77.4 
 
 92.1 
 
 63.4 
 
 11.2 
 
 2^365 
 
 93011 
 
 St Blue 
 
 2510 
 
 2506 
 
 Do. 
 
 77.2 
 
 41.4 
 
 40.7 
 
 79.1 
 
 91.9 
 
 63.7 
 
 10.8 
 
 2.175 
 
 93108 
 
 StG 
 
 2474 
 
 2473 
 
 May 6, 1918 
 
 73.9 
 
 39.3 
 
 38.8 
 
 80.6 
 
 92.8 
 
 62.9 
 
 10.2 
 
 1.900 
 
 93111 
 
 StG 
 
 2474 
 
 2473 
 
 Do. 
 
 70.8 
 
 39.0 
 
 38.7 
 
 79.4 
 
 92.6 
 
 63.7 
 
 10.1 
 
 1.765 
 
 93112 
 
 Blue 
 
 2474 
 
 2473 
 
 Do. 
 
 73.3 
 
 40.0 
 
 38.9 
 
 77.7 
 
 89.7 
 
 63.2 
 
 11.1 
 
 2.150 
 
 93159 
 
 A 
 
 2511 
 
 2506 
 
 June 14, 1918 
 
 65.9 
 
 37.9 
 
 38.8 
 
 72.9 
 
 85.0 
 
 58.1 
 
 9.7 
 
 
 93160 
 
 StG 
 
 2511 
 
 2506 
 
 Do. 
 
 72.6 
 
 40.4 
 
 42.5 
 
 77.7 
 
 87.8 
 
 63.4 
 
 10 9 
 
 2^440 
 
 93162 
 
 StG 
 
 2511 
 
 2506 
 
 Do. 
 
 75.6 
 
 40.8 
 
 40.8 
 
 83.7 
 
 95.3 
 
 67.3 
 
 11.8 
 
 2,460 
 
 93192 
 
 StG 
 
 2430 
 
 2434 
 
 June 14, 1918 
 
 67.0 
 
 37.5 
 
 37.1 
 
 74.6 
 
 87.0 
 
 58.1 
 
 9.6 
 
 1,760 
 
 93195 
 
 G 
 
 2430 
 
 2434 
 
 Do. 
 
 74.2 
 
 40.7 
 
 40.7 
 
 83.8 
 
 99.0 
 
 65.8 
 
 10.8 
 
 2,420 
 
 93201 
 
 A 
 
 2576 
 
 2506 
 
 Do. 
 
 72.8 
 
 40.5 
 
 40.4 
 
 80.0 
 
 89.8 
 
 62.1 
 
 10.2 
 
 2,340 
 
 93209 
 
 A 
 
 2509 
 
 2506 
 
 Do. 
 
 71.9 
 
 40.3 
 
 39.9 
 
 74.6 
 
 86.5 
 
 61.3 
 
 10.4 
 
 1,950 
 
 93210 
 
 StG 
 
 2509 
 
 2506 
 
 Do. 
 
 70.9 
 
 40.3 
 
 41.7 
 
 75.2 
 
 85.4 
 
 60.7 
 
 11.1 
 
 2.070 
 
 93212 
 
 B 
 
 2509 
 
 2506 
 
 Do. 
 
 70.3 
 
 40.8 
 
 40.7 
 
 82.1 
 
 94.7 
 
 65.5 
 
 11.1 
 
 
 93240 
 
 G 
 
 2451 
 
 2506 
 
 June 15, 1918 
 
 63.7 
 
 38.7 
 
 39.5 
 
 72.8 
 
 82.8 
 
 58.5 
 
 9.9 
 
 1.700 
 
 93301 
 
 StG 
 
 2436 
 
 2434 
 
 June 16, 1918 
 
 75.0 
 
 41.6 
 
 41.3 
 
 82.9 
 
 94.9 
 
 65.9 
 
 10.2 
 
 2.670 
 
 93370 
 
 A 
 
 2437 
 
 2434 
 
 July 18, 1918 
 
 77.5 
 
 42.0 
 
 40.8 
 
 81.9 
 
 94.5 
 
 64.5 
 
 10 8 
 
 2,050 
 
 93371 
 
 A 
 
 2437 
 
 2434 
 
 Do. 
 
 72.7 
 
 38.9 
 
 39.9 
 
 78.0 
 
 90.1 
 
 61.7 
 
 10.7 
 
 2,050 
 
 93377 
 
 St Blue 
 
 2508 
 
 2506 
 
 July 20, 1918 
 
 73.0 
 
 40.0 
 
 40.7 
 
 77.3 
 
 91.0 
 
 62.9 
 
 10.6 
 
 1,810 
 
 93379 
 
 B 
 
 2508 
 
 2506 
 
 Do. 
 
 69.6 
 
 38.7 
 
 39.8 
 
 76.8 
 
 88.9 
 
 64.3 
 
 9.8 
 
 1.840 
 
 93397 
 
 B 
 
 2510 
 
 2506 
 
 July 23, 1918 
 
 77.4 
 
 42.0 
 
 42.3 
 
 82.0 
 
 95.0 
 
 67.1 
 
 10.8 
 
 2.325 
 
 93421 
 
 Blue 
 
 2474 
 
 2473 
 
 July 4, 1918 
 
 71.2 
 
 39.5 
 
 39.8 
 
 81.1 
 
 94.8 
 
 66.7 
 
 10.6 
 
 2.075 
 
 93423 
 
 StG 
 
 2474 
 
 2473 
 
 Do. 
 
 75.8 
 
 40.3 
 
 40.3 
 
 84.7 
 
 99.0 
 
 68.7 
 
 11.1 
 
 2.140 
 
 93447 
 
 A 
 
 2451 
 
 2506 
 
 Aug. 16, 1918 
 
 76.3 
 
 42.2 
 
 41.3 
 
 78.2 
 
 89.8 
 
 64.0 
 
 11.2 
 
 2,200 
 
 93450 
 
 St G 
 
 2451 
 
 2506 
 
 Do. 
 
 
 
 
 
 
 
 
 
 93476 
 
 A 
 
 2576 
 
 2506 
 
 Do! 
 
 
 
 
 
 
 
 9.8 
 
 
 93479 
 
 G 
 
 2576 
 
 2506 
 
 Do. 
 
 
 
 
 
 
 
 9.7 
 
 
 93511 
 
 A 
 
 2509 
 
 2506 
 
 Do. 
 
 75.5 
 
 42'3 
 
 43 '3 
 
 78.9 
 
 88.5 
 
 62.9 
 
 11.1 
 
 2,475 
 
 93513 
 
 StG 
 
 2509 
 
 2506 
 
 Do. 
 
 70.8 
 
 37.6 
 
 40.9 
 
 76.0 
 
 87.7 
 
 63.4 
 
 10.7 
 
 1.795 
 
 93527 
 
 StG 
 
 2511 
 
 2506 
 
 Do. 
 
 77.0 
 
 41.8 
 
 41.8 
 
 82.6 
 
 93.8 
 
 65.7 
 
 11.1 
 
 2.675 
 
 93528 
 
 B 
 
 2511 
 
 2506 
 
 Do. 
 
 76.2 
 
 41.8 
 
 41.2 
 
 82.8 
 
 95.8 
 
 66.8 
 
 10.9 
 
 2.250 
 
 93531 
 
 A 
 
 2511 
 
 2506 
 
 Do. 
 
 77.3 
 
 41.0 
 
 42.0 
 
 83.5 
 
 97.6 
 
 67.5 
 
 11.9 
 
 2.525 
 
 93532 
 
 A 
 
 2511 
 
 2506 
 
 Do. 
 
 73.3 
 
 40.0 
 
 41.0 
 
 77.5 
 
 87.8 
 
 1 4 
 
 10.2 
 
 2.360 
 
 93560 
 
 StG 
 
 2507 
 
 2506 
 
 Aug. 20, 1918 
 
 74.7 
 
 42.3 
 
 41.1 
 
 77.8 
 
 89.4 
 
 63.6 
 
 11.2 
 
 2.170 
 
 93652 
 
 A 
 
 2510 
 
 2506 
 
 Nov. 2, 1918 
 
 
 37.8 
 
 37.9 
 
 77.2 
 
 89.2 
 
 63.2 
 
 10 7 
 
 
 93654 
 
 StG 
 
 2510 
 
 2506 
 
 Do. 
 
 72.7 
 
 38.4 
 
 40.1 
 
 76.7 
 
 89.1 
 
 62 . 5 
 
 10.3 
 
 2^050 
 
 93655 
 
 StG 
 
 2510 
 
 2506 
 
 Do. 
 
 
 
 
 79.9 
 
 92.1 
 
 
 10.9 
 
 
 93657 
 
 A 
 
 2436 
 
 2434 
 
 Do. 
 
 79.0 
 
 40.8 
 
 40.4 
 
 87.6 
 
 103.0 
 
 70.0 
 
 11.3 
 
 2^380 
 
 93658 
 
 A 
 
 2436 
 
 2434 
 
 Do. 
 
 72.7 
 
 41.4 
 
 42.0 
 
 80.5 
 
 93.6 
 
 63.0 
 
 10.1 
 
 2.260 
 
 93659 
 
 StG 
 
 2436 
 
 2434 
 
 Do. 
 
 75.6 
 
 42.4 
 
 41.8 
 
 85.6 
 
 100.6 
 
 67.1 
 
 10.7 
 
 2.645 
 
 93661 
 
 A An 
 
 2432 
 
 2434 
 
 Do. 
 
 78.8 
 
 40.6 
 
 40.4 
 
 88.3 
 
 102.0 
 
 fi9.4 
 
 11.4 
 
 2,500 
 
 93663 
 
 A 
 
 2432 
 
 2434 
 
 Do. 
 
 79.3 
 
 42.3 
 
 41.4 
 
 87.5 
 
 102.8 
 
 68 . 7 
 
 10 9 
 
 2,630 
 
 93826 
 
 Blue 
 
 2474 
 
 2473 
 
 Feb. 25, 1919 
 
 74.3 
 
 41.5 
 
 39.9 
 
 82.2 
 
 96.4 
 
 05 - 9 
 
 11.5 
 
 2.190 
 
 93836 
 
 G 
 
 2511 
 
 2866 
 
 Do. 
 
 75.0 
 
 39.3 
 
 41.0 
 
 77.3 
 
 91.8 
 
 64.1 
 
 10.9 
 
 2.125
 
 48 GENETIC STUDIES OF RABBITS AND RATS. 
 
 TABLE 33. Descriptive list of rabbits studied-Continued. 
 VIII. F,, POLISH X FLEMISH Continued. 
 
 Uun.' 
 
 Color. 
 
 s 
 
 | 
 
 Born. 
 
 Skull-length. 
 
 Anterior 
 1 Bkull-width. 
 
 1 .Posterior 
 skull-width. 
 
 Femur. 
 
 P 
 
 H 
 
 1 
 
 1 
 
 93839 
 
 A 
 
 2451 
 
 2866 
 
 Feb. 27, 1919 
 
 J7.7 
 
 9.3 
 
 0.0 
 
 72.5 
 
 85.1 
 
 8.7 
 
 0.2 
 
 .710 
 
 93843 
 
 Q 
 
 2451 
 
 2866 
 
 Do. 
 
 re. 8 
 
 10.4 
 
 0.1 
 
 81.0 
 
 92.3 
 
 55.9 
 
 1.3 
 
 ,315 
 
 93850 
 
 B 
 
 2576 
 
 2866 
 
 Feb. 25, 1919 
 
 r4.6 
 
 1.0 
 
 1.3 
 
 80.0 
 
 90.9 
 
 2.6 
 
 0.5 
 
 .255 
 
 93852 
 
 Blue 
 
 2576 
 
 2866 
 
 Do. 
 
 59.8 
 
 0.6 
 
 9.5 
 
 76.4 
 
 89.1 
 
 1.4 
 
 0.3 
 
 ,770 
 
 93858 
 
 StG 
 
 2510 
 
 2866 
 
 Do. 
 
 73.8 
 
 0.4 
 
 0.5 
 
 82.4 
 
 93.5 
 
 6.3 
 
 1.3 
 
 ,130 
 
 93883 
 
 B 
 
 2509 
 
 2866 
 
 Do. 
 
 58.5 
 
 7.2 
 
 0.0 
 
 73.1 
 
 82.5 
 
 7.5 
 
 0.0 
 
 ,780 
 
 93884 
 
 B 
 
 2509 
 
 2866 
 
 Do. 
 
 58.7 
 
 8.3 
 
 9.7 
 
 75.8 
 
 88.3 
 
 0.6 
 
 0.8 
 
 .765 
 
 9 3v* 
 
 luGAn 
 
 2436 
 
 2434 
 
 Do. 
 
 70.1 
 
 9.6 
 
 tO. 3 
 
 82.0 
 
 95.2 
 
 5.0 
 
 0.5 
 
 ,920 
 
 94039 
 
 B 
 
 2511 
 
 2866 
 
 May 5. 1919 
 
 70.0 
 
 8.7 
 
 9.8 
 
 80.7 
 
 93.1 
 
 64.5 
 
 0.6 
 
 
 94067 
 
 Blue 
 
 2431 
 
 2433 
 
 Mar. 15, 1919 
 
 74.3 
 
 1.4 
 
 9.8 
 
 82.7 
 
 95.9 
 
 63.9 
 
 0.9 
 
 '.370 
 
 c?2911 
 
 Blue 
 
 2436 
 
 2434 
 
 Apr. 16, 1918 
 
 74.0 
 
 2 i 
 
 1.8 
 
 86.3 
 
 98.0 
 
 65.3 
 
 1.0 
 
 ,000 
 
 c?2912 
 
 BlueG 
 
 2436 
 
 2434 
 
 Do. 
 
 74.6 
 
 2.2 
 
 1.8 
 
 78.7 
 
 93.2 
 
 3.3 
 
 0.2 
 
 ,200 
 
 of 2919 
 
 B 
 
 2509 
 
 2506 
 
 Apr. 17. 1918 
 
 
 
 
 
 
 
 1.5 
 
 
 rf2935 
 
 A 
 
 2437 
 
 2434 
 
 Do. 
 
 76.5 
 
 2.1 
 
 0.9 
 
 86.3 
 
 00.4 
 
 6.9 
 
 1.5 
 
 ^225 
 
 c?2936 
 
 Y 
 
 2437 
 
 2434 
 
 Do. 
 
 80.2 
 
 0.6 
 
 1.6 
 
 85.1 
 
 99.1 
 
 6.0 
 
 1.0 
 
 ,380 
 
 0*2937 
 
 StG 
 
 2437 
 
 2434 
 
 Do. 
 
 70.4 
 
 1.4 
 
 0.9 
 
 77.9 
 
 92.2 
 
 2.8 
 
 9.8 
 
 ,025 
 
 o"2940 
 
 A 
 
 2430 
 
 2434 
 
 Do. 
 
 68.9 
 
 9.3 
 
 0.4 
 
 80.5 
 
 91.0 
 
 1.4 
 
 0.6 
 
 
 c?2941 
 
 Y 
 
 2430 
 
 2434 
 
 Do. 
 
 68.5 
 
 
 
 81.5 
 
 95.7 
 
 2.8 
 
 0.2 
 
 
 c?2980 
 
 B 
 
 2432 
 
 2434 
 
 Apr. 18, 1918 
 
 77.0 
 
 2.0 
 
 2.5 
 
 83.5 
 
 97.4 
 
 7.4 
 
 0.8 
 
 ,315 
 
 d"2981 
 
 A 
 
 2432 
 
 2434 
 
 Do. 
 
 69.3 
 
 9.3 
 
 0.4 
 
 
 88.0 
 
 60.5 
 
 9.5 
 
 .910 
 
 d"2998 
 
 BlueG 
 
 2511 
 
 2506 
 
 Apr. 19, 1918 
 
 74.4 
 
 1.4 
 
 40.6 
 
 80.8 
 
 96.8 
 
 65.0 
 
 1.1 
 
 .050 
 
 0*2999 
 
 StG 
 
 2511 
 
 2506 
 
 Do. 
 
 76.6 
 
 1.6 
 
 41.5 
 
 83.3 
 
 99.4 
 
 66.0 
 
 1.9 
 
 ,450 
 
 tfSOOl 
 
 G 
 
 2576 
 
 2506 
 
 Do. 
 
 
 
 
 
 
 
 11.7 
 
 
 (73003 
 
 B 
 
 2576 
 
 2506 
 
 Do. 
 
 3.7 
 
 1 .1 
 
 41.0 
 
 78.8 
 
 91.3 
 
 62.7 
 
 10.3 
 
 2,035 
 
 c?3005 
 
 A 
 
 2510 
 
 2506 
 
 Do. 
 
 2.8 
 
 l.< 
 
 39.8 
 
 75.1 
 
 87.7 
 
 61.5 
 
 10.5 
 
 1,900 
 
 d"3006 
 
 B 
 
 2510 
 
 2506 
 
 Do. 
 
 71.8 
 
 41.4 
 
 40.0 
 
 76.3 
 
 90. 
 
 61.6 
 
 10.0 
 
 1,890 
 
 0*3109 
 
 B 
 
 2474 
 
 2473 
 
 May 6, 1918 
 
 71.1 
 
 40.4 
 
 39.0 
 
 76.9 
 
 90.9 
 
 H.< 
 
 10.4 
 
 1.780 
 
 c?3110 
 
 B 
 
 2474 
 
 2473 
 
 Do. 
 
 70. 
 
 39.9 
 
 40.0 
 
 76. 
 
 89.3 
 
 60.8 
 
 10.5 
 
 1,765 
 
 d3113 
 
 A 
 
 2474 
 
 2473 
 
 Do. 
 
 67.0 
 
 40.3 
 
 38.9 
 
 75.0 
 
 86. 
 
 57. 
 
 10.2 
 
 1,560 
 
 d>3193 
 
 StG 
 
 2430 
 
 2434 
 
 June 14, 1918 
 
 72.8 
 
 40.0 
 
 40. 
 
 82.5 
 
 95. 
 
 64. 
 
 10. 
 
 1,880 
 
 0"3194 
 
 B 
 
 2430 
 
 2434 
 
 Do. 
 
 70.9 
 
 40. 
 
 39.9 
 
 78.5 
 
 88. 
 
 61. 
 
 10. 
 
 2.020 
 
 c73196 
 
 Blue 
 
 2430 
 
 2434 
 
 Do. 
 
 75.0 
 
 41.8 
 
 40.6 
 
 83. 
 
 98. 
 
 65. 
 
 10. 
 
 2.175 
 
 d*3197 
 
 G 
 
 2576 
 
 2506 
 
 Do. 
 
 74. 
 
 42.5 
 
 42.0 
 
 80. 
 
 94. 
 
 63. 
 
 10. 
 
 2.250 
 
 (73199 
 
 B 
 
 2576 
 
 2506 
 
 Do. 
 
 74. 
 
 42. 
 
 42. 
 
 78. 
 
 90. 
 
 62. 
 
 10. 
 
 2,080 
 
 (73200 
 
 A 
 
 2576 
 
 2506 
 
 Do. 
 
 73. 
 
 41. 
 
 40. 
 
 78. 
 
 89. 
 
 62. 
 
 10. 
 
 1,930 
 
 C73222 
 
 B An 
 
 2432 
 
 2434 
 
 Do. 
 
 78. 
 
 41. 
 
 42. 
 
 84. 
 
 100. 
 
 66. 
 
 11. 
 
 2,160 
 
 d*3239 
 
 G 
 
 2451 
 
 2506 
 
 June 15, 1918 
 
 72. 
 
 42. 
 
 42. 
 
 77. 
 
 87. 
 
 61. 
 
 10. 
 
 1,895 
 
 0^3241 
 
 StG 
 
 2451 
 
 2506 
 
 Do. 
 
 77. 
 
 43. 
 
 42. 
 
 81. 
 
 94. 
 
 65. 
 
 11. 
 
 2,200 
 
 <73298 
 
 A 
 
 2436 
 
 2434 
 
 June 16, 1918 
 
 76. 
 
 41. 
 
 42. 
 
 88. 
 
 104. 
 
 70. 
 
 11. 
 
 2.410 
 
 cf3299 
 
 A An 
 
 2436 
 
 2434 
 
 Do. 
 
 72. 
 
 41. 
 
 10. 
 
 80. 
 
 95. 
 
 65. 
 
 10. 
 
 1,790 
 
 0*3300 
 
 A 
 
 2436 
 
 2434 
 
 Do. 
 
 72. 
 
 41. 
 
 41. 
 
 82. 
 
 98. 
 
 64. 
 
 10. 
 
 2.260 
 
 (73302 
 
 StG 
 
 2436 
 
 2434 
 
 Do. 
 
 75. 
 
 41. 
 
 41. 
 
 81. 
 
 93. 
 
 64. 
 
 10. 
 
 2,260 
 
 <73304 
 
 StG 
 
 2510 
 
 2506 
 
 June 17, 1918 
 
 79. 
 
 45. 
 
 44. 
 
 85. 
 
 97. 
 
 69. 
 
 12. 
 
 2.515 
 
 (73367 
 
 StG 
 
 2437 
 
 2434 
 
 July 18, 1918 
 
 73. 
 
 41. 
 
 40. 
 
 83. 
 
 99. 
 
 63. 
 
 11. 
 
 2,280 
 
 C73368 
 
 G 
 
 2437 
 
 2434 
 
 Do. 
 
 75. 
 
 42. 
 
 43. 
 
 84. 
 
 100. 
 
 67. 
 
 10. 
 
 2,390 
 
 0*3396 
 
 A 
 
 2510 
 
 2506 
 
 July 23, 1918 
 
 70. 
 
 40 
 
 40. 
 
 82. 
 
 95. 
 
 65. 
 
 10. 
 
 
 c73398 
 
 StG 
 
 2510 
 
 2506 
 
 Do. 
 
 72. 
 
 42. 
 
 43. 
 
 79. 
 
 93. 
 
 64. 
 
 11. 
 
 2,125 
 
 d*3391 
 
 B 
 
 2510 
 
 2506 
 
 Do. 
 
 69. 
 
 39. 
 
 41. 
 
 79. 
 
 92. 
 
 62. 
 
 10. 
 
 
 c73400 
 
 StG 
 
 2510 
 
 2506 
 
 Do. 
 
 72. 
 
 40. 
 
 41. 
 
 77. 
 
 86. 
 
 62. 
 
 10. 
 
 1,880 
 
 <73420 
 
 StG 
 
 2474 
 
 2473 
 
 July 4, 1918 
 
 69. 
 
 39. 
 
 39. 
 
 76. 
 
 89. 
 
 61. 
 
 9. 
 
 1,760 
 
 C73448 
 
 StG 
 
 2451 
 
 2506 
 
 Do. 
 
 77. 
 
 42. 
 
 42. 
 
 86. 
 
 97. 
 
 70. 
 
 12. 
 
 2,450 
 
 0*3449 
 
 G 
 
 2451 
 
 2506 
 
 Do. 
 
 74. 
 
 42. 
 
 41. 
 
 80. 
 
 92. 
 
 65. 
 
 10. 
 
 2,180 
 
 <73480 
 
 G 
 
 2576 
 
 2506 
 
 Do. 
 
 74. 
 
 41. 
 
 41. 
 
 79. 
 
 92. 
 
 61. 
 
 10. 
 
 2.125 
 
 (7348 
 
 B 
 
 2576 
 
 2506 
 
 Do. 
 
 74. 
 
 42. 
 
 41. 
 
 78. 
 
 90. 
 
 61. 
 
 10. 
 
 1,975 
 
 cf3529 
 
 StG 
 
 2511 
 
 2506 
 
 Do. 
 
 71. 
 
 40. 
 
 40. 
 
 80. 
 
 92. 
 
 64. 
 
 10. 
 
 2.130 
 
 o"3533 
 
 StG 
 
 2511 
 
 2506 
 
 Do. 
 
 73. 
 
 40. 
 
 41. 
 
 82. 
 
 95. 
 
 66. 
 
 11. 
 
 2.300 
 
 0*3534 
 
 B 
 
 2511 
 
 2506 
 
 Do. 
 
 71. 
 
 40. 
 
 41. 
 
 80. 
 
 96. 
 
 67. 
 
 10. 
 
 2,195
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 49 
 
 TABLE 33. Descriptive lift of rabbits studied Continued. 
 VIII. F 2 , POLISH X FLEMISH Continued. 
 
 Designa- 
 tion. 
 
 Color. 
 
 Mother. 
 
 Father. 
 
 Born. 
 
 Skull-length. 
 
 Anterior 
 skull-width. 1 
 
 Posterior 
 skull-width. 
 
 J 
 
 1 
 
 a 
 
 1 
 
 i 
 1 
 
 ^3603 
 
 A An 
 
 2430 
 
 2434 
 
 Aug. 1, 1918 
 
 75.0 
 
 42.7 
 
 41.6 
 
 88.3 
 
 101.9 
 
 69.0 
 
 11.7 
 
 2.335 
 
 d"3604 
 
 B 
 
 2430 
 
 2434 
 
 Do. 
 
 76.3 
 
 42.2 
 
 41.7 
 
 87.5 
 
 100.5 
 
 69.1 
 
 11.4 
 
 2.485 
 
 c?3656 
 
 A An 
 
 2436 
 
 2434 
 
 Nov. 2, 1918 
 
 74.6 
 
 41.2 
 
 41.4 
 
 83.8 
 
 96.2 
 
 64.6 
 
 10.2 
 
 2,110 
 
 cT3660 
 
 StG 
 
 2436 
 
 2434 
 
 Do. 
 
 71.1 
 
 39.6 
 
 40.7 
 
 80.9 
 
 93.5 
 
 64.2 
 
 9.6 
 
 2.150 
 
 d"3662 
 
 A 
 
 2432 
 
 2434 
 
 Do. 
 
 79.9 
 
 41.5 
 
 42.4 
 
 87.3 
 
 101.2 
 
 69.7 
 
 12.1 
 
 2,450 
 
 d"3664 
 
 Blue 
 
 2432 
 
 2434 
 
 Do. 
 
 71.7 
 
 40.7 
 
 41.3 
 
 82.2 
 
 96.8 
 
 65.5 
 
 9.9 
 
 1,900 
 
 c?3665 
 
 B An 
 
 2432 
 
 2434 
 
 Do. 
 
 77.8 
 
 42.2 
 
 41.9 
 
 86.9 
 
 102.2 
 
 68.4 
 
 10.9 
 
 2.450 
 
 d"3838 
 
 StG 
 
 2511 
 
 2866 
 
 Feb. 25, 1919 
 
 67.9 
 
 39.3 
 
 40.8 
 
 79.5 
 
 93.5 
 
 62.7 
 
 10.3 
 
 1,920 
 
 cT3841 
 
 G 
 
 2451 
 
 2866 
 
 Feb. 27, 1919 
 
 75.2 
 
 41.0 
 
 41.8 
 
 75.7 
 
 88.2 
 
 58.8 
 
 10.8 
 
 1.645 
 
 c?3849 
 
 A 
 
 2576 
 
 2866 
 
 Feb. 25, 1919 
 
 68.9 
 
 40.0 
 
 41.0 
 
 74.9 
 
 88.4 
 
 59.6 
 
 9.8 
 
 1.730 
 
 d"3851 
 
 B 
 
 2576 
 
 2866 
 
 Do. 
 
 70.7 
 
 41.5 
 
 40.1 
 
 78.0 
 
 91.1 
 
 61.8 
 
 10.4 
 
 2.025 
 
 cf3853 
 
 BlueG 
 
 2576 
 
 2866 
 
 Do. 
 
 71.1 
 
 41.4 
 
 41.2 
 
 78.7 
 
 90.6 
 
 61.2 
 
 10.7 
 
 1.870 
 
 c?3859 
 
 B 
 
 2510 
 
 2866 
 
 Do. 
 
 71.6 
 
 39.9 
 
 41.0 
 
 79.0 
 
 90.7 
 
 60.5 
 
 10.3 
 
 1.850 
 
 d"3878 
 
 A 
 
 2437 
 
 2434 
 
 Feb. 24, 1919 
 
 72.0 
 
 41.5 
 
 41.8 
 
 81.9 
 
 98.1 
 
 63.5 
 
 10.3 
 
 2.000 
 
 cf3882 
 
 G 
 
 2509 
 
 2866 
 
 Feb. 25, 1919 
 
 69.3 
 
 40.8 
 
 41.5 
 
 78.9 
 
 90.9 
 
 64.3 
 
 11.2 
 
 1,970 
 
 C"3889 
 
 DilY 
 
 2436 
 
 2434 
 
 Feb. 24, 1919 
 
 73.5 
 
 42.5 
 
 42.8 
 
 86.0 
 
 99.5 
 
 65.4 
 
 10.7 
 
 2,100 
 
 d"4035 
 
 StG 
 
 2511 
 
 2866 
 
 May 5, 1919 
 
 73.4 
 
 39.6 
 
 40.4 
 
 78.1 
 
 93.6 
 
 63.4 
 
 10.8 
 
 2,010 
 
 c?4037 
 
 A 
 
 2511 
 
 2866 
 
 Do. 
 
 67.6 
 
 38.2 
 
 37.8 
 
 71.3 
 
 84.9 
 
 56.3 
 
 9.3 
 
 1,675 
 
 c?4066 
 
 StG 
 
 2436 
 
 2433 
 
 Do. 
 
 70.3 
 
 41.7 
 
 40.8 
 
 80.3 
 
 95.4 
 
 62.8 
 
 9.8 
 
 1.800 
 
 c?4068 
 
 YAn 
 
 2432 
 
 2434 
 
 Mar. 3, 1919 
 
 73.0 
 
 40.8 
 
 40.9 
 
 85.2 
 
 101.2 
 
 66.3 
 
 11.5 
 
 1.920 
 
 IX. Fj, HIMALA YAN X FLEMISH. 
 
 
 
 
 
 
 ' 
 
 _L 
 
 1 
 
 | 
 
 
 
 
 
 
 Designa- 
 tion. 
 
 Color. 
 
 . 
 
 
 Born. 
 
 1 
 
 L 
 
 J^. 
 
 
 
 
 
 
 , 
 
 
 
 1 
 
 1 
 
 
 3 
 
 a! 
 
 || 
 
 3 
 
 Q 
 
 ;| 
 
 
 
 H 
 
 1? 
 
 
 
 I 
 
 t 
 
 
 & 
 
 3* 
 
 I 5 
 
 & 
 
 
 & 
 
 1 
 
 
 
 92983 
 
 H 
 
 2646 
 
 2647 
 
 Apr. 18, 1918 
 
 74.6 
 
 41.8 
 
 41.5 
 
 81.9 
 
 93.9 
 
 64.4 
 
 10.8 
 
 2,220 
 
 92985 
 
 G 
 
 2646 
 
 2647 
 
 Do. 
 
 78.8 
 
 38.9 
 
 40.4 
 
 83.7 
 
 96.4 
 
 65.3 
 
 12.3 
 
 2,125 
 
 92987 
 
 B 
 
 2646 
 
 2647 
 
 Do. 
 
 80.8 
 
 40.7 
 
 41.0 
 
 88.3 
 
 101.4 
 
 67.6 
 
 11.9 
 
 2,535 
 
 92988 
 
 B 
 
 2646 
 
 2647 
 
 Do. 
 
 76.5 
 
 41.8 
 
 41.8 
 
 82.4 
 
 94.7 
 
 64.0 
 
 11.3 
 
 2,400 
 
 93024 
 
 B 
 
 2517 
 
 2522 
 
 Apr. 20, 1918 
 
 75.0 
 
 41.8 
 
 40.4 
 
 84.7 
 
 98.2 
 
 68.4 
 
 11.6 
 
 2.675 
 
 93025 
 
 G 
 
 2517 
 
 2522 
 
 Do. 
 
 76.9 
 
 41.8 
 
 42.0 
 
 82.9 
 
 96.3 
 
 66.1 
 
 11.7 
 
 2,900 
 
 93026 
 
 StG 
 
 2517 
 
 2522 
 
 Do. 
 
 73.0 
 
 41.3 
 
 42.8 
 
 84.4 
 
 96.7 
 
 67.5 
 
 12.2 
 
 2.590 
 
 93054 
 
 G 
 
 2521 
 
 2522 
 
 Apr. 22, 1918 
 
 78.5 
 
 40.1 
 
 39.7 
 
 84.4 
 
 97.9 
 
 66.6 
 
 11.3 
 
 2.160 
 
 93149 
 
 G 
 
 2517 
 
 2522 
 
 June 14. 1918 
 
 75.9 
 
 41.5 
 
 40.7 
 
 82.9 
 
 94.0 
 
 66.8 
 
 12.1 
 
 2.680 
 
 93150 
 
 StG 
 
 2517 
 
 2522 
 
 Do. 
 
 76.0 
 
 40.8 
 
 41.7 
 
 84.4 
 
 94.9 
 
 68.0 
 
 12.0 
 
 2,480 
 
 93151 
 
 StG 
 
 2517 
 
 2522 
 
 Do. 
 
 76.1 
 
 42.6 
 
 41.8 
 
 87.3 
 
 98.9 
 
 69.7 
 
 12.7 
 
 2.380 
 
 93153 
 
 H 
 
 2521 
 
 2522 
 
 Do. 
 
 77.1 
 
 41.4 
 
 40.5 
 
 88.8 
 
 101.3 
 
 71.4 
 
 12.1 
 
 2.705 
 
 93157 
 
 B 
 
 2521 
 
 2522 
 
 Do. 
 
 74.4 
 
 41.5 
 
 41.5 
 
 83.9 
 
 97.3 
 
 67.4 
 
 11.7 
 
 2.290 
 
 93202 
 
 B 
 
 2646 
 
 2647 
 
 Do. 
 
 78.3 
 
 41.9 
 
 42.7 
 
 81.9 
 
 93.2 
 
 64.0 
 
 11.1 
 
 2.440 
 
 93228 
 
 StG 
 
 2645 
 
 2647 
 
 Do. 
 
 77.5 
 
 44.7 
 
 43.4 
 
 85.4 
 
 97.0 
 
 69.4 
 
 12.0 
 
 2,880 
 
 93373 
 
 G 
 
 2519 
 
 2522 
 
 July 20, 1918 
 
 75.4 
 
 39.6 
 
 39.6 
 
 81.9 
 
 95.7 
 
 65.4 
 
 11.7 
 
 2.400 
 
 93375 
 
 G 
 
 2519 
 
 2522 
 
 Do. 
 
 77.2 
 
 40.2 
 
 40.8 
 
 82.6 
 
 93.0 
 
 65.4 
 
 11.3 
 
 2.070 
 
 93385 
 
 G 
 
 2642 
 
 2647 
 
 June 27. 1918 
 
 77.3 
 
 40.5 
 
 40.5 
 
 82.4 
 
 95.9 
 
 65.5 
 
 11.0 
 
 2.850 
 
 93387 
 
 StG 
 
 2642 
 
 2647 
 
 Do. 
 
 
 
 
 
 
 
 10. S 
 
 
 93389 
 
 StG 
 
 2642 
 
 2647 
 
 Do. 
 
 74.4 
 
 40.9 
 
 41L3 
 
 81A 
 
 95.0 
 
 ee's 
 
 11.3 
 
 2^520 
 
 93439 
 
 H 
 
 2517 
 
 2522 
 
 Aug. 16, 1918 
 
 76.8 
 
 42.1 
 
 42.2 
 
 87.3 
 
 99.6 
 
 69.6 
 
 11.1 
 
 2.750 
 
 93441 
 
 StG 
 
 2517 
 
 2522 
 
 Do. 
 
 69.8 
 
 38.9 
 
 38.4 
 
 79.2 
 
 90.9 
 
 63.1 
 
 10 9 
 
 2.260 
 
 93442 
 
 StG 
 
 2517 
 
 2522 
 
 Do. 
 
 75.9 
 
 41.9 
 
 40.4 
 
 87.9 
 
 100.5 
 
 71.0 
 
 11.8 
 
 2.900
 
 50 
 
 GENETIC STUDIES OF RABBITS AND RATS. 
 
 TABLE 33. Descriptive list of rabbits studied Continued. 
 IX. Ft, HIM ALATANX FLEMISH Continued. 
 
 DwiKn.i- 
 tion. 
 
 Color. 
 
 | 
 
 1 
 
 Born. 
 
 Skull-length. 
 
 Anterior skull- 1 
 width. 
 
 Posterior skull- 1 
 width. 
 
 Femur. 
 
 08 
 3 
 
 H 
 
 Humerus. 
 
 a 
 W 
 
 J3 
 . 
 
 93443 
 
 B 
 
 2517 
 
 2522 
 
 Aug. 16, 1918 
 
 79.1 
 
 42.3 
 
 42.9 
 
 87.5 
 
 101.0 
 
 69.8 
 
 12.6 
 
 2,530 
 
 93444 
 
 8tG 
 
 2517 
 
 2522 
 
 Do. 
 
 73.3 
 
 40.9 
 
 41.9 
 
 82.7 
 
 93.8 
 
 67.6 
 
 11.1 
 
 2,410 
 
 93505 
 
 G 
 
 2645 
 
 2647 
 
 Do. 
 
 76.1 
 
 38.7 
 
 40.7 
 
 84.0 
 
 95.6 
 
 67.3 
 
 11.0 
 
 2.440 
 
 93523 
 
 G 
 
 2521 
 
 2522 
 
 Do. 
 
 78.0 
 
 43.3 
 
 41.7 
 
 86.5 
 
 99.1 
 
 69.6 
 
 11.5 
 
 2,560 
 
 93526 
 
 G 
 
 2521 
 
 2522 
 
 Do. 
 
 74.0 
 
 40.1 
 
 40.8 
 
 81.5 
 
 92.5 
 
 65.0 
 
 11.0 
 
 2,275 
 
 93570 
 
 G 
 
 2830 
 
 2647 
 
 Aug. 21, 1918 
 
 83.8 
 
 45.3 
 
 45.2 
 
 89.0 
 
 100.5 
 
 69.2 
 
 11 .8 
 
 2.710 
 
 93596 
 
 G 
 
 2646 
 
 2647 
 
 Sept. 1, 1918 
 
 77.8 
 
 42.8 
 
 42.7 
 
 87.3 
 
 98.6 
 
 67.3 
 
 12.8 
 
 2.750 
 
 93600 
 
 H 
 
 2646 
 
 2647 
 
 Do. 
 
 81.3 
 
 43.5 
 
 43.8 
 
 89.5 
 
 100.0 
 
 69.7 
 
 12.7 
 
 2,990 
 
 93601 
 
 G 
 
 2646 
 
 2647 
 
 Do. 
 
 79.8 
 
 42.7 
 
 42.9 
 
 88.7 
 
 101.7 
 
 70.8 
 
 11.8 
 
 2,620 
 
 93647 
 
 H 
 
 2519 
 
 2522 
 
 Nov. 2, 1918 
 
 74.2 
 
 41.0 
 
 42.4 
 
 83.5 
 
 95.5 
 
 64.6 
 
 11.6 
 
 2,500 
 
 (73023 
 
 H 
 
 2517 
 
 2522 
 
 Apr. 20, 1918 
 
 
 
 
 
 
 
 12.1 
 
 
 C73056 
 
 G 
 
 2521 
 
 2522 
 
 Apr. 22, 1918 
 
 76!s 
 
 41.2 
 
 4l!i 
 
 86.1 
 
 99.5 
 
 
 12.2 
 
 
 (73057 
 
 G 
 
 2521 
 
 2522 
 
 Do. 
 
 79.3 
 
 41.7 
 
 41.9 
 
 85.1 
 
 97.4 
 
 66^3 
 
 11.3 
 
 
 (73145 
 
 H 
 
 2517 
 
 2522 
 
 June 14, 1918 
 
 74.8 
 
 41.0 
 
 41.6 
 
 84.6 
 
 96.2 
 
 67.3 
 
 11.2 
 
 2,185 
 
 (73147 
 
 StG 
 
 2517 
 
 2522 
 
 Do. 
 
 74.8 
 
 42.2 
 
 42.5 
 
 88.4 
 
 95.4 
 
 67.5 
 
 11.9 
 
 2,170 
 
 rf-3148 
 
 StG 
 
 2517 
 
 2522 
 
 Do. 
 
 72.5 
 
 41.9 
 
 42.4 
 
 82.6 
 
 96.4 
 
 67.7 
 
 11.3 
 
 2,190 
 
 (73156 
 
 G 
 
 2521 
 
 2522 
 
 Do. 
 
 73.8 
 
 40.9 
 
 41.2 
 
 83.2 
 
 96.5 
 
 67.1 
 
 10.8 
 
 2.300 
 
 C73158 
 
 B 
 
 2521 
 
 2522 
 
 Do. 
 
 74.3 
 
 41.3 
 
 41.2 
 
 81.2 
 
 94.2 
 
 64.9 
 
 11.1 
 
 2,300 
 
 C73204 
 
 G 
 
 2646 
 
 2647 
 
 Do. 
 
 76.6 
 
 41.8 
 
 42.5 
 
 83.9 
 
 97.4 
 
 66.2 
 
 12.0 
 
 2,455 
 
 (73206 
 
 G 
 
 2646 
 
 2647 
 
 Do. 
 
 73.6 
 
 42.8 
 
 43.1 
 
 78.9 
 
 93.0 
 
 63.1 
 
 10.7 
 
 2,450 
 
 (73208 
 
 G 
 
 2646 
 
 2647 
 
 Do. 
 
 73.1 
 
 
 
 81.5 
 
 96.6 
 
 64.6 
 
 11.1 
 
 
 <73227 
 
 StG 
 
 2645 
 
 2647 
 
 Do. 
 
 76.9 
 
 43^4 
 
 44.0 
 
 83.7 
 
 96.0 
 
 66.4 
 
 11.5 
 
 2,480 
 
 <73372 
 
 H 
 
 2519 
 
 2522 
 
 July 20, 1918 
 
 
 
 
 84.9 
 
 98.3 
 
 67.7 
 
 11.6 
 
 2,350 
 
 c73386 
 
 StG 
 
 2642 
 
 2647 
 
 June 27, 1918 
 
 
 
 
 
 
 
 10.8 
 
 
 C73388 
 
 StG 
 
 2642 
 
 2647 
 
 Do. 
 
 
 
 
 
 
 
 10.8 
 
 
 (73445 
 
 StG 
 
 2517 
 
 2522 
 
 Aug. 16, 1918 
 
 75^7 
 
 41.9 
 
 42^6 
 
 87.2 
 
 106 'o 
 
 70'2 
 
 11.3 
 
 2,470 
 
 C73446 
 
 B 
 
 2517 
 
 2522 
 
 Do. 
 
 78.0 
 
 41.8 
 
 41.5 
 
 90.3 
 
 102.8 
 
 71.0 
 
 12.1 
 
 2,440 
 
 c73496 
 
 G 
 
 2831 
 
 2647 
 
 Do. 
 
 76.2 
 
 43.4 
 
 43.0 
 
 86.7 
 
 98.1 
 
 70.7 
 
 11.3 
 
 2,555 
 
 <73497 
 
 G 
 
 2831 
 
 2647 
 
 Do. 
 
 77.0 
 
 42.3 
 
 42.7 
 
 86.9 
 
 99.9 
 
 70.8 
 
 10.9 
 
 2,690 
 
 (73503 
 
 H 
 
 2645 
 
 2647 
 
 Do. 
 
 77.9 
 
 42.1 
 
 42.5 
 
 82.9 
 
 93.2 
 
 64.6 
 
 11.8 
 
 2,460 
 
 (73504 
 
 H 
 
 2645 
 
 2647 
 
 Do. 
 
 77.8 
 
 43.2 
 
 44.0 
 
 83.4 
 
 95.8 
 
 66.4 
 
 11.0 
 
 2,490 
 
 (73506 
 
 G 
 
 2645 
 
 2647 
 
 Do. 
 
 76.2 
 
 40.6 
 
 42.4 
 
 80.3 
 
 91.5 
 
 62.7 
 
 11.2 
 
 2,430 
 
 c73507 
 
 G 
 
 2645 
 
 2647 
 
 Do. 
 
 77.6 
 
 40.6 
 
 42.6 
 
 85.4 
 
 95.5 
 
 68.2 
 
 12.0 
 
 2,390 
 
 (73508 
 
 G 
 
 2645 
 
 2647 
 
 Do. 
 
 81.2 
 
 44.2 
 
 43.1 
 
 88.8 
 
 100.7 
 
 69.8 
 
 12.8 
 
 2.740 
 
 (73509 
 
 StG 
 
 2645 
 
 2647 
 
 Do. 
 
 70.8 
 
 40.4 
 
 41.3 
 
 80.8 
 
 90.3 
 
 64.9 
 
 11.2 
 
 2,190 
 
 <73520 
 
 B 
 
 2521 
 
 2522 
 
 Do. 
 
 70.4 
 
 40.9 
 
 40.0 
 
 81.9 
 
 95.6 
 
 65.0 
 
 10.6 
 
 2.070 
 
 (73524 
 
 G 
 
 2521 
 
 2522 
 
 Do. 
 
 76.1 
 
 40.4 
 
 40.3 
 
 86.0 
 
 99.8 
 
 67.2 
 
 11.2 
 
 2.170 
 
 (73525 
 
 G 
 
 2521 
 
 2522 
 
 Do. 
 
 76.3 
 
 41.3 
 
 41.6 
 
 86.1 
 
 98.9 
 
 67.8 
 
 11.4 
 
 2.305 
 
 (73568 
 
 G 
 
 2830 
 
 2647 
 
 Aug. 21, 1918 
 
 80.3 
 
 42.3 
 
 42.7 
 
 85.2 
 
 98.1 
 
 67.2 
 
 11.1 
 
 2.420 
 
 (f8M9 
 
 G 
 
 2830 
 
 2647 
 
 Do. 
 
 
 
 
 
 
 64.0 
 
 10.6 
 
 
 C73697 
 
 G 
 
 2646 
 
 2647 
 
 Sept. 1, 1918 
 
 8CK3 
 
 41.8 
 
 42.6 
 
 88.6 
 
 101.6 
 
 68.1 
 
 11.6 
 
 2.525 
 
 4*8606 
 
 G 
 
 2646 
 
 2647 
 
 Do. 
 
 79.9 
 
 42.0 
 
 43.2 
 
 84.6 
 
 98.7 
 
 67.5 
 
 12.0 
 
 2.500 
 
 (P85M 
 
 G 
 
 2646 
 
 2647 
 
 Do. 
 
 80.3 
 
 41.9 
 
 44.7 
 
 89.5 
 
 101.9 
 
 71.2 
 
 12.0 
 
 2,350 
 
 c73602 
 
 G 
 
 2646 
 
 2647 
 
 Do. 
 
 83.7 
 
 44.0 
 
 45.0 
 
 89.7 
 
 105.4 
 
 71.5 
 
 12.4 
 
 2,870 
 
 rf'SMI 
 
 H 
 
 2519 
 
 2522 
 
 Nov. 2, 1918 
 
 73.0 
 
 43.4 
 
 43.0 
 
 88.0 
 
 99.8 
 
 70.3 
 
 12.3 
 
 2,595 
 
 i?M4i 
 
 H 
 
 2519 
 
 2522 
 
 Do. 
 
 77.2 
 
 43.9 
 
 44.4 
 
 89.4 
 
 103.2 
 
 69.8 
 
 12.9 
 
 2.640 
 
 <73650 
 
 G 
 
 2519 
 
 2522 
 
 Do. 
 
 71.9 
 
 40.7 
 
 40.9 
 
 82.7 
 
 99.1 
 
 66.2 
 
 11.6 
 
 2.070
 
 PART II, 
 
 ON A NON-TRANSMISSIBLE TRI-COLOR VARIATION 
 
 IN RATS. 
 
 In the course of studies of linkage in rats, I have observed the 
 production of a tri-color individual, gray, yellow, and white, similar 
 to the tri-color varieties of guinea-pig, and I had hoped to establish 
 from it a new color variety of rat, but thus far no success has at- 
 tended my efforts. The case, in its bearings on the nature and origin 
 of variations, is not without interest, and so will be described briefly. 
 
 The two genes whose linkage relations were being investigated 
 when the tri-color individual made its appearance have been desig- 
 nated c and p. Both are recessive in crosses and thus become visible 
 as somatic characters only when present in the homozygous state, 
 cc or pp respectively. An individual of the formula cc is an albino; 
 an individual of the formula pp is pink-eyed and yellow-coated. 
 
 When an ordinary albino is crossed with a pink-eyed yellow indi- 
 vidual, young are produced which are neither albinos nor pink-eyed 
 yellow, since neither c nor p will be homozygous in the cross-bred 
 individuals, which are in fact gray in color like wild rats, or else 
 gray-hooded, if the gene for hooded pattern is present in homozygous 
 condition. By means of such crosses between albino and pink-eyed 
 yellow rats, gray and gray-hooded young were being produced when 
 the tri-color individual made its appearance. It is a gray-hooded 
 individual, like its brothers and sisters, except that the areas nor- 
 mally gray are liberally mottled with yellow. The mottling extends 
 practically throughout the colored portions of the coat from nose 
 to tail tip. The yellow areas vary in size from those which contain 
 merely a few yellow hairs to those of a square inch in extent. The 
 least yellow is found on the right shoulder, which is almost like 
 normal gray in appearance. The most yellow is found in the middle 
 of the back, to the left of the median line, where a large spot of 
 clear yellow occurs in the wide back-stripe of the hooded pattern, 
 which would correspond roughly with grade +2j/ of the grading 
 scale used in our studies of hooded rats. 
 
 The tri-color individual is, fortunately for the purposes of genetic 
 study, a male. He has been mated with albinos, with pink-eyed 
 yellows, and with gray FI cross-breds between the albino and the 
 pink-eyed yellow races, and later with his own daughters of the 
 colors white, pink-eyed yellow, and gray. Hundreds of young have 
 been produced by these matings, for the animal is a remarkably 
 large and vigorous one and his mates have proved very prolific, but 
 
 51
 
 52 GENETIC STUDIES OF RABBITS AND RATS. 
 
 not one of the young was mottled like the sire. This occasioned no 
 surprise when the mates were not related to the tri-color male or 
 were not his direct descendants, for it was conjectured that he might 
 be a mutant due to a new recessive gene, which accordingly would 
 only become visible when in a homozygous state. But if he him- 
 self represented such a homozygous recessive combination, all his 
 gametes should transmit the mottled condition, and all his daugh- 
 ters consequently should be heterozygous for the mottled condition, 
 and in matings with their sire should produce 50 per cent of mottled 
 individuals. The fact that they do not produce mottled individuals 
 shows this hypothesis to be untenable. 
 
 The tri-color male, in fact, breeds like his gray-hooded brothers 
 and sisters, producing gametes which are commonly either c or p, 
 but which in no case transmit a mosaic relationship. From his 
 ancestry and from the results of his matings, we know him to be a 
 double heterozygote, CcPp. The Mendelian expectation is that he 
 will form four kinds of gametes, cP, Cp, CP, and cp, but since there 
 exists linkage (in this case repulsion) between c and p, the first two 
 classes of gametes will be commoner than the other two. His 
 breeding behavior accords with these expectations. In most of his 
 gametes he transmits either albinism or pink-eyed yellow. In an 
 occasional gamete he probably transmits both, a matter which has 
 not been tested, as it would require special matings. It is certain 
 that in an occasional gamete he transmits neither c nor p, a condition 
 expressed hi the formula CP, which like cp would represent a cross- 
 over. His gametes, accordingly, appear to be such as are normally 
 produced by Fi doubly heterozygous individuals like his gray and 
 gray-hooded brothers and sisters. 
 
 How, then, can we account for the production of yellow areas in 
 the gray coat? By an explanation similar to that which Morgan 
 and Bridges (1919 1 ) have given to account for the production of 
 gynandromorphs in Drosophila. We may suppose that at an early 
 cleavage (perhaps the first) of the fertilized egg from which this rat 
 developed, one of the pair of chromosomes, in which the genes c 
 and p are borne, failed to divide as normally, or that for some other 
 reason it failed to pass into one of the cell-products. Further con- 
 sideration shows that it must have been the maternal rather than 
 the paternal chromosome of this pair which was lost. For the mother 
 was an albino and must have contributed cP, but the father was a 
 pink-eyed yellow, Cp, and his contribution by itself would produce 
 yellow fur, whereas with the mother's contribution it would pro- 
 duce gray. We may suppose, accordingly, that a blastomere con- 
 taining only the paternal contribution produced that part of the 
 
 > Carnegie Inat. Wash. Pub. No. 278.
 
 GENETIC STUDIES OF RABBITS AND RATS. 53 
 
 skin which is yellow, and that a blastomere or blastomeres contain- 
 ing as normally both maternal and paternal members of this chromo- 
 some pair produced the gray part of the coat. 
 
 But how about the germ-cells of this individual? Does the mixed 
 condition seen in the coat obtain also among the germ-cells? Very 
 likely it does. But if so, no tri-color progeny need be expected in 
 consequence. For those germ-cells which correspond in composition 
 with the gray parts of the coat would produce gametes like those of 
 any other FI individual, which for the most part would transmit 
 either albinism or pink-eyed yellow, with an occasional gamete 
 transmitting gray and an occasional gamete transmitting both albin- 
 ism and pink-eyed yellow. But the germ-cells corresponding to 
 the yellow parts of the coat would transmit either pink-eyed yellow 
 or nothing (so far as the chromosome under discussion is concerned). 
 It is an open question whether this last type of gamete (lacking the 
 entire chromosome) would be viable, and if it were, its existence would 
 be difficult to detect, since it would behave like the double recessive 
 type of gamete, cp, in its effects on coat color. 
 
 How, then, could a genuine genetically transmissible type of 
 mottled rat arise? Only, I suppose, by a change in the genetic 
 locus at P, p, so that it became, instead of P alone or p alone, a 
 mosaic Pp transmissible as a unit and capable of functioning as the 
 allelomorph either of P or of p. Such apparently is the case in the 
 guinea-pig, where Ibsen has shown the mottled condition to be the 
 allelomorph of both simple black and simple yellow. Such appar- 
 ently is also the condition in the mottled variety of rabbit called 
 "Japanese," which I have recently studied in a series of crosses, and 
 such would appear to be the case in maize with striped pericarp, 
 which has been extensively studied by Emerson and his associates. 
 They find that the mosaic factor frequently becomes simple by 
 mutation either to all red or to all white, and that mutation occurs 
 oftenest to that component of the mosaic which is most extensive 
 in the parent. This result is easily understood if we suppose that 
 the mosaic "gene" divides in such a way as to include more of one 
 of its components than of the other in a cell product, or so as to 
 contain only the major component in a cell product. That cell 
 would then develop into a self-colored individual. I think that 
 this idea of a mosaic gene will explain the high degree of variability 
 which is found not only in striped maize, but also in spotted mam- 
 mals, whether spotted with yellow or with white. Hooded rats and 
 Dutch rabbits are examples of spotted mammals which I have stud- 
 ied extensively and have found to be amenable to selection like the 
 striped pericarp of maize studied by Emerson and by Hays, probably 
 for the same reason, viz, because a mosaic gene varies (or, if you 
 prefer, "mutates") in the proportions of its constituents.
 
 54 GENETIC STUDIES OF RABBITS AND RATS. 
 
 In 1912 1 I described a peculiar guinea-pig, which, in the light of 
 the present case, I am inclined to explain in the same way as the 
 tri-color rat, as a non-transmissible though not of necessity a purely 
 somatic mutation. At that time I characterized the guinea-pig in 
 question as a "pink-eyed individual with a colored coat," but this 
 is not a very good description for it. The description fits better a 
 genuine genetically transmissible variety that was then unknown to 
 us, but which curiously enough was soon to appear in our breeding- 
 pens from stock that had recently been obtained in Peru. The indi- 
 vidual, whose peculiarities were not transmitted to its offspring, 
 was by pedigree a heterozygote between albinism and pale black. 
 Such a heterozygote I believe it in fact to have been, but in appearance 
 it was white, except for some small spots of pale black ("blue") on 
 the right side of the head and on the hips. The head pigmentation 
 extended as a "faint pigmented streak" on to "the iris of each 
 eye." The mother of this animal was blue, the father cream (which 
 is recessive to blue), but he also transmitted albinism. He can not 
 have transmitted blue, since that is dominant to cream. Undoubt- 
 edly, then, the egg from which this individual developed transmitted 
 color (C) and blue (E) which lie in different chromosomes. But 
 the father transmitted albinism (c) and cream (e), which are reces- 
 sive allelomorphs of C and E respectively. Evidently it was the 
 maternal chromosome bearing C which was lost from the greater 
 part of the ectoderm of the embryo, since no other loss would have 
 produced an uncolored coat and eye. Whether or not E was lost 
 in the same regions can not be determined, but since all colored 
 areas were blue, not cream, it is evident that wherever C was re- 
 tained, E was retained also. 
 
 The peculiar individual was a female and produced three young, 
 all albinos as I recall, by an albino sire, before her untimely death. 
 It can not be stated, therefore, whether the germ-cells were hetero- 
 zygous in nature or were like the greater part of the coat, pure albino, 
 inherited from the sire alone. Certainly none of the three develop- 
 ing ova transmitted the mosaic condition found in the mother. It 
 seems probable, though it is regrettably unverifiable, that no young 
 mottled like the mother would have been obtained, had we been 
 able to obtain a much larger number of young. 
 
 1 Science. 36, p. 508.
 
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 Carnegie Inst. Wash. Pub. No. 196, pp. 51-55. 
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 Jour. Morph., 34, 1-68. 
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 No. 196, pp. 1-49, 9 figs. 
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 PUNNETT, R. C. 1912. Inheritance of coat-colour in rabbits. Jour. Genetics, 2, pp. 
 
 221-238, pi. 12-14. 
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 Genetics, 5, pp. 37-50. 
 . 1918. Genetic studies in rabbits. I. On the inheritance of weight. Jour. 
 
 Genetics 8, 1-25. 
 WRIGHT, SEWALL. 1918. On the nature of size factors Genetics, 3, 367-374. 
 
 55
 
 PLATE 1 
 
 P, Polish 9~2, mother of F, yonm: 
 //, Himalayan 91, mother of FI yi 
 /', Flemish (lianl V 7, color steel u 
 The relative si/.e is ronerllv >ho\\: 
 
 oosefl with hotli the uther races. 
 in en. r- \vitli Imth the other races 
 mother of FI young bv a Polish sire. 
 :cent in the case of the Polish in-
 
 PLATE 2 
 
 Skull and certain leg Ixines of representative individuals of the three pure races of i.-il.liiis 
 and of their Fj hybrids, shown on the same scale of reduction in size. To the left of the skull 
 of each rabbit is seen the tibia-fibula, and to the right of the skull the femur of the ri^ht hind- 
 leg. Below the skull is seen the right humerus. 
 
 P, bones of Polish 9 9. F, bones of Flemish 97, shown alive in plate 1, /'. //, Uu,- ..i 
 Himalayan 96. F u P X F, l>ones of 92436, daughter of Flemish 97 and of Polish o"3. F,, 
 P X H, bones of 92320, daughter of Polish 99 and of Himalayan c?5. FI, H X F. Inn,.- ..f 
 92431, daughter of Himalayan 90 and Flemish cT2.
 
 431
 
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