64 



INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



The data demonstrate that among these individuals the strongest germs — the 

 germs of highest efficiencj^ in the accomphshment of development — were produced 

 by the earher birds of the season. The two individuals from the very first eggs of 

 the season, and those from the last several eggs of the season, were completely or 

 almost completely infertile. Almost completely fertile birds (females) arose from 

 the early season. There appears in these results, moreover, a higher degree of 

 fertility in the females than in the males. The probable bearing of this fact has 

 been already pointed out. The data indicate, therefore, that the low levels of 

 fertihty, attained by experimental means — late season with overwork — are levels 

 which not only influence the sex of offspring as shown elsewhere, but that the func- 

 tion of fertility which is thus forced to new levels tends to propagate itself in 

 inheritance upon such newly formed or enforced levels. 



9 481 T. orientali 

 In summer of 1912 this female wa 

 (unmated). 



St. alba cf 215 given 5/1/13. 

 3/20/13; (cold) (first in life). 



Table 29. 

 9-10; 6/14/14; 48+ luo. 

 ; G/ll/ll;3/15/i:i; 21 'a nio. 

 ; G/25/11; alive 10/1/14; 4II-|- m. 

 with 9 489; winter 1912-13 witi 



ather 412; cf 412 died 3/15/13 



B. 5/14/13; not incubated.' 



C. 5/23; not incubated. 



D. 6/1; not incubated. 



E. 6/5/13, from perch and bruken.= 



F. S/5; from perch and broken. 



G. 8/9-10; from perch and broken. 



A. 1/2/14; not incubated. 



B. 1/27; not incubated. 



C. 3/8; not incubated. 



D. 3/16; no trace development. 



E. 3/26; no trace developi 



F. 4/11; not incubated. 



G. 5/2; no development. 

 H. 5/2S; no development. 



c? 715 Si. alba; 8/28/13; alive 10/ 

 This male given 6/16/14, when it was active a 

 (421) given; no result; c? 421 died 1/1/15. 



13+ mo. 



tile. On7/10(uii 



' Advantage was taken of the opportunity here offered to study the .si'je relations of the egg-yolks of a fu 

 clutches each of a single egg. 



2 The nesting habits of this bird were never normal. Several of her eggs were sliglitlj' broken. 



T.\BLE .30. 

 cT St. alba (672) ; about Augu.st. 1912 (from dealer); 

 9 T.orientalis (429); 8/8/11; alive 10/1/14; 3+ yi 

 5/11/13; first in life; shell roughened with calcareous nodules. 



A 2. 5/12/13; soft shell. 



5/27; from perch; broken. 

 5/29; not tested. 



6/6-7; from perch; broken. 



6/14; no development. 

 6/16; no development. 



6/22; from perch; broken. 

 6/24; no development. 



6/30; no development. 

 7/2; no development. 



7/10; from perch; broken. 

 7/12; no development. 



7/18; from perch; broken. 

 7/20; white; 714; dead 11/20/ 



I. 7/26/13 (bird confined) no development. 



J 1. 8/4; 1 

 J 2. 8/6; 1 



I development. 

 I development. 



8/13; no development. 

 8/16 or 17; from perch, 



8/23; no development. 

 8/25; no development. 



N 1. 9/3; no development. 



N 2. 9/5; on ground, no development. 



O 1. 9/13; no development. 



O 2. 9/15; no development. 



