142 



INHERITANCE, I'ERTILITY, AND SEX IN PIGEONS. 



half-l 



thor ++. 



C 1. 7/22; no development. 

 C 2. 7/24; no development. 



Table 125 [cnnUniinl.) 

 Pair S. 

 c T alba -ris. x ri.s.-alba X tur. X X l is. XX X t urtur (13 4) ; 5/1.3/0.3; (inbred) 

 9 alba^ris. X ris.-alba X turtur (D 2) ; 4/22/60; half-sister ++. 

 4/12/04; little or no development. 

 4/14/04; little or no development. 



D 1. 8/7; no record, 

 D 2. 8/9; no record. 

 Pair 4. 

 J T. turtur X T. orientalis hyb. (TO 5) ; 0/6/04; .ilive 6/15/15; 11 + yr. 

 6/15/15; 1+yr. 



C 1. 5/29; hatched; dark; alive 6/10/15. 

 C 2. 5/31; hatched; dark; alive 6/16/15. 

 Escaped 6/1/05. 



5/23; no development. 

 5/25; no development. 



E 1. 3/27/05; no development. 

 E 2. 3/29/05; no development. 



F 1. 4/29; no record. 

 F 2. probably not laid. 



9 albax risoria (580); 4/29/14; 

 5/11/15; hatched; dark; alive 6/16/15. 

 5/13/15; hatched; dark; accident 6/16/15. 



SEX-RATIO IN CROSSES OF FAMILIES, SUBFAMILIES, AND GENERA. 



A summary of the data on the sex-ratio in tlie three groups of crosses considered 

 in this chapter is given in table 12G. It will be seen that first crosses which involve 

 members of different Jamilies or of different suhjamilies yield only ( ?) males. In both 

 of these groups, particularly where one parent is hybrid, an occasional offspring 

 without sex-glands is produced. When individuals belonging merely to different 

 genera — in this case rather closely related genera — are crossed, both male and 

 female young are produced. 



There is reason to believe that different species vary in their tendency to produce 

 male and female ofTspring; and that St. alba, for example, is one that can more 

 readily than many others be made to yield a predominance of female offspring. 

 But this form, along with others, has been shown to change in this capacity with 

 respect to width of cross, season, overwork, etc. Regardless of what the differences 

 among the various species in initial tendency to produce a given sex may mean, 

 the data of this volume point out at least several of the conditions which act in 

 such a way as most materially to modify the actual production of sex. 



Table 126. — Sex-ratio in family, subfamily, and generic crosses. 



' Very minute testes. 



2 The female common pigeon (C. tabellaria f) of unknown 

 17 young (Icf, 3 ?9). is not included in this tabulation. 



' Eight of these were from a mating that gave Icf to 8 9 . 



with a Itybrid male, hatched 



