44 INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



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

 in hfe, 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 tlie entire series, but which, 

 like the "mutational" character, were accentuated at (he 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 left: Japanese turtle "mutant" No. lOS and mate No. 433. 



These are the parents of the other birds shown on this plnlc I'lic whitened "mutant" parent is shown to the 

 left; the normal mate to the right. All birds of this plate ph. it , ri ;i 1 >li'' I Srpi . 29, 1912. " No. 108 was hatched Sept. 

 22, 1910. On Oct. 12, it is found that the dark centers of tli.' juwual fcMthcrs are reijlaced by while! The bird is a 

 close copy of No. 98, and whitened for the same reason— I he .//./ </,/, ..f llic dam and nil^nnlnni. l'liolii<;ra)ih('d m 

 full Juvenal plumage Nov. 25, 1910." (The photoKra|)lis (akcii X.iv. 2.',. lilll), prnvcl iinsuil able lui- irpi,„lu.-l kh; : 

 tlicv served, however, to show that the later pluniaw's nl this bird were mil ]i(Tcrptibl\- clilTririil fniiu llic lirsl 

 plumaKC,— Ed.) 



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

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



Figure on right: The eariiest 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 interveninp; normal young from the pai-ents shown 



under A. 



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

 second partial "mutant." 



Middle figure: l-Vm dc Xo. SSO with normal coloration throughout. In last, plumage preceding death, however, 

 there appeared several \\liiirn(d feathers. 



Figure on right : I'l nialc X.i. Sol with whitened tail and .some gray and wliilc in flight feathers. This was the 

 third partial "mut.ant ' of the .series. 



C. The last three "mutant" offspring of "niuttuit" No. 108 and normal No. 433. 



Figure on left : Female \o, S7 1 : t he fom'th partial "mutant" of the season. Not oidy the tail, but some primaries, 

 .secondarii'>, .mkI ii>iii;iI- \\r\r hii.- wliiicni'd. 



Middl. lii:iiii M ilr X.I s,,'): mir ,,i the last pair of "mutants;" from the extreme end of the season. This bird 



has a while lail; ^ily uiay Pi wliilr iirimarics, secondaries, tertials, and body coverts generally. Whole a.spect 



extremely light. Tlie 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) ami but a single Uidncy. 



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



