BLOND AND WHITE RING-DOVES CROSSED WITH MOURNING-DOVES, ETC. 



133 



second, is also well shown when the eggs of the pure species are used. This latter situation 

 is not true of eggs produced by the hybrid risoria X alba. In the mating of the tumbler with a 

 pure ring the first egg shows greater developmental power in 6 cases, less in 2 cases; and 

 both of these two exceptions pertain to the first clutch of the year. On the other hand, 

 when the same tumbler was mated to a risoria X alba hybrid the second egg of the clutch 

 showed greater developmental power in 5 cases and less developmental power in 3 cases. 



The difficulty of getting hybrids from wide crosses and the added difficulty which 

 arises when either of the members of the cross is itself a hybrid is illustrated in the record 

 (table 113) of a laticauda X risoria male to a female tumbler. Only 3 eggs of 24 tested 

 showed any development. These eggs were from adjacent clutches of early June and middle 

 July and all were hatched. The second egg of the latter clutch was the egg that failed. 



Homer X ring. — A mating between a male blond ring and a female homer yielded 40 

 eggs (from October 1898 to March 1900, data not tabulated), 35 of which were tested; 

 1 hatched, 1 developed to hatching and failed; 1 produced a 13-day embryo, while a fourth 

 egg developed a small embryo. The male was later found to be fully fertile with ring-doves, 

 but infertile with a female Chinese turtle-dove {Sp. chinensis). (X 10, X 4) 



The reciprocal of this cross, namely, a male homer and a female ring-dove, was 

 more successful. The result of a mating made 18 months before the beginning of 

 the cross just described is detailed in tabic 115. From this mating 10 of the 13 



