GO INHERITANCE, FERTILITY, AND SEX IN PIGEONS. 



(108), half of her eggs were hatched, and several other eggs showed well-developed 

 embryos. The fourth female (489) lived 20 months and laid no eggs. 



The fifth female (429) was left with other male and female T. orientalis until 

 15 months old without indication of desire to mate. Early in May 1913, however, 

 this bird while unmated laid her first eggs. She was thereafter mated with a St. 

 alba (672) ; the mating proved very infertile. She was remated September 30, 1913, 

 to learn whether she would prove more fertile with a male (69) of her own species. 

 It will be noted that very many of her eggs had peculiar shells roughened with 

 calcareous nodules, or were soft and defective. That maternal instincts were also 

 awry in this female is shown by habitual egg-laying from the perch. A comparison 

 of the data of the two matings (table 30) shows that when female 429 was mated 

 with a male of her own species she was very plainly more fertile than when mated 

 with St. alba.* From this latter mating only one egg of 17 tested showed any 

 trace of development; this one hatched. The mating with one of her own species, 

 though a brother to her father, yielded eggs showing some development in 7 of the 

 9 tests; 2 of these developed near to hatching. The considerable numbers of 

 untested eggs, usually broken or defective, were used in other studies. 



The sixth female (454) lived for 19 months, and although constantly with males 

 of her own kind she laid no eggs and showed no signs of mating. The seventh (475) 

 has a similar history. The eighth and ninth females had a slightly shorter term of 

 life, but like the preceding remained with their mature brothers without producing 

 eggs, and without showing any indication of their sex, or of desire to mate. 



FERTILITY OF MALES OF THE SERIES. 



Three of the 7 known males showed no signs of mating and never won mates; 

 this evident deficiency of Nos. 452, 412, and 488 is all that was learned of them. 

 It has been noted that 5 of the known females show a similar history. It may 

 here be added that 3 members of this family escaped or disappeared without having 

 revealed their sex by means of eggs or mating behavior. Successful tests were made 

 of the fertility of 4 males; 3 proved absolutely infertile. Reference to these tests 

 will be made after the single case of partial fertility is described. 



The original data on the fertility of male 421 is given in table 31. The bird 

 was tested with 3 different females. He mated when only a year old, but at this 

 time (1912) only the slightest fertility was in evidence. Even in the earlier months 

 of 1913 fertility was still too low. Finally, all of the 20 eggs from the mating of 

 1914 were absolutely infertile, though the birds were frequently seen to copulate. 

 On July 16 it was decided to replace this male with a St. alba (715) to see whether 

 the complete infertility might be traceable in part to the female. That this was 

 not so is shown by the record (table 32), from which it appears that notwith- 

 standing the lateness of the season and the previous overwork, this female was still 

 fairly fertile with the new male. There can therefore be no doubt whatever that 

 "weak sperm" of male 421 is responsible 9 for the uniform lack of development 

 in the earlier part of the season. No. 421 acquired his weakness by inbreeding 

 and through his origin from an egg produced late in the season, under conditions 



8 Possibly part or much of this difference in fertility for two successive years may be due to ageing; it is unsafe 

 to press such comparisons very far. 



'This male died January 1915 (very tubercular); it had no right leslis discoverable at autopsy; a diminutive left 

 testia; a very large tubercle involving whole of spleen, and possibly the whole of another left gonad. 



