200 



Bulletin No. 155.— 1913. 



When we compare these deductions with the results actually 

 obtained in experiments as presented on p. 177, it is apparent that 

 the experimental results come fairly close to the expected. Of 43 

 birds described when over 3 weeks old, 25 were barred and 18 were 

 black; and in each group the sex-ratios were approximately 1:1. 



Second Instance. — cf 325 B (barred) X 9 32oE (white); first 

 possibility: We may consider first the case in which 9 32oE is 

 assumed to have the zygotic formula C2BbFfIi, compatible with 

 heterozygous barring rendered obscure by heterozygous /. As 

 before, cf 325B may be assumed to form gametes, 



CBfi • Cbfi 

 while the 9 325E, forms gametes, 



CbFI • CbFi ■ CBfl • CBfi 

 The mating would then be represented : 



9 CbFI ■ CbFi • CBfl - CBfi X 

 d^ CBfi 'Cbfi = 



d^d" 



[C2i56/2/^ white 

 I CoBofJi, white 

 C 'iBbf 212, barred 

 ^2^2/222, barred 



99-; 



[C262F///, white 

 C2BbFfIi, white 

 C2BbFfi2, barred 



[C2b2Ffi2,h\a,ck 



These data may be summarized as follows : 



