44 INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



The eggs which produced these "mutant" young were at the same time her last 

 in life, though she lived more than 15 months after their production, and was then 

 killed only by rather exceptional exposure. Very probably, however, she would 

 have laid other eggs if she had been able to gain a perch and copulate. These 

 things she was unable to do because in the late summer of 1912, at the close of the 

 overwork incident to the production of the series of eggs now under discussion, she was 

 unable adequately to renew her flight and tail feathers. Indeed, she remained 

 permanently quite unable to renew more than a fraction of her plumage; at the 

 time of death she was provided with very few body coverts and most other feathers 

 were stunted and incomplete. It will thus be seen that the mother of this group 

 of young was plainly a weaker organism at the extreme end of the season, 

 when the dominance of the father's mutational characteristics became complete. 

 The general weakness of the two parents no doubt cooperated in additional 

 defects, abnormalities, and weakness which obtained in the entire series, but which, 

 like the "mutational" character, were accentuated at the very end of the series. 



But if some shall incline to assume that a germinal basis a basis of genetic 

 significance is not involved in this instance and that these features might have 

 been purely somatic in their nature, such assumptions may be brought to face the 

 following further facts : 



(1) The two most strikingly mutant young the very last of the season had 

 "club feet" (in addition to the whitened mutational plumage), and one of these 



EXPLANATION OF PLATE 7. 



A. Figure on loft: Japanese turtle "mutant" No. 108 and mate No. 433. 



These are the parents of the other birds shown on this plate. The whitened "mutant" parent is shown to the 

 left; the normal mate to the right. All birds of this plate photographed Sept. 29, 1912. "No. 108 was hatched Sept. 

 22, 1910. On Oct. 12, it is found that the dark centers of the juvcnal feathers are replaced by white! The bird is a 

 close copy of No. 98, and whitened for the same reason -the old age of the dam and inbreeding. Photographed in 

 full juvenal plumage Nov. 25, 1910." (The photographs taken Nov. 25, 1910, proved unsuitable for reproduction; 

 they served, however, to show that the later plumages of this bird were not perceptibly different from the first 

 plumage. ED.) 



Middle figure: One of the earlier normal offspring (891) of the above pair. The coloration was quite normal. 

 Before death, however, the plumage of this bird showed a decided tendency to whiten. 



Figure on right: The earliest of the young (826) of this series which was photographed. The bird was photo- 

 graphed in strong light, but the coloration was perfectly normal. 



B. The first two partial "mutants" and an intervening normal young from the parents shown 



under A. 



Figure on left: Male No. 879 with whitened tail-feathers, and with otherwise normal coloration. This was the 

 second partial "mutant." 



Middle figure: Female No. 880 with normal coloration throughout. In last plumage preceding death, however, 

 there appeared several whitened feathers. 



Figure on right: Female No. 8(31 with whitened tail and some gray and white in flight feathers. This was the 

 third partial "mutant" of the series. 



( :. The last three "mutant" offspring of "mutant" No. 108 and normal No. 433. 



Figure on left: Female No. 874; the fourth partial " mutant " of the season. Not only the tail, but some primaries, 

 secondaries, and tertials were here whitened. 



.Middle figure: Male No. 859; one of the last pair of "mutants;" from the extreme end of the season. This bird 

 haa a white tail; mostly gray to white primaries, secondaries, tertials, and body coverts generally. Whole aspect 

 extremely light. The feathering, particularly the primaries, was deficient in first and in later plumages. The bird 

 had a "club foot" (the left). 



Figure on right: No. 801 (sex ?); last "mutant;" nest-mate of above bird and quite similar to it in color and 

 feathering. It also had "club feet" (one of which is shown in the illustration) and but a single kidney. 



For the origin of the several young shown on this plate see table 20. 



