RESULTS OF HYBRIDIZING RING-DOVES. 303 



'09, p. 194). Through the courtesy of Mrs. Whitman, I am 

 permitted to give exact statistics as copied from Professor Whit- 

 man's records. These were known in a general way to me, 

 having been discussed in conversations before his death, and 

 they are as follows: when white male ring-doves were crossed 

 with dark female ring-doves 5 blonds and 4 whites were obtained. 

 White male ring-doves crossed with females of the very distinct 

 species, Turturhumilis, produced five dark birds and twelve whites. 

 In both crosses the white offspring were all females and the dark 

 hybrids were all males " so far as was known." 



There being no white FI male hybrids, it was impossible to 

 get Fa offspring from the white hybrids, and the white hybrids 

 were consequently crossed back upon the original white stock 

 (see Table VII.). All of the offspring of this cross were white, 

 and males as well as females appeared. A white male was also 

 obtained in a cross between a blond male and a white female 

 both birds being the offspring of hybrids crossed back on the 

 original stock (see Table XII.). 



A blond hybrid male which had been obtained by crossing 

 back was mated with a pure blond female, and all of the five 

 offspring were blonds. Three of the four birds whose sex was 

 learned were females. The effects upon the sex ratio of crossing 

 back upon the original stock will be discussed later in this paper. 

 Other results are given in Tables V., VI., VIII. -XI. and XIII.- 

 XVII. 



In looking over these results, it is quite apparent that white- 



TABLE V. 



BLOND Fi HYBRID MALE (TABLE I.) X BLOND FEMALE. MATING 22. 

 Offspring 9 blonds: 5 males, i female, 3 sex ?. 

 5 whites: 4 females and i sex ?. 



B.d" B.9 W. 9 



B.c? W. 9 B.9 (Original Stock.) 



