SEX-LINKAGE IN FOWLS 509 
Bateson and Punnett (11) describe certain exceptions occur- 
ring in their sex-linkage experiment with fowls, which they sug- 
gest may be due to a failure of the usual association between 
the sex-linked facotr and the sex-determiner, 1.e., to ‘crossing 
over’ in the female. This is what I mean by partial sex-linkage. 
The sex-linked factor in canaries transforms pink eyes to black, 
and may then be represented by the symbol B. The following 
crosses have been reported by Durham and Marryatt (08): 
Black o BM BM 
Pink 9? bM bm 
BM BM we blac a9. 
BM bm —black 9 a 
F, black «7 BMbM 
Black @ BM bm 
BM BM —black & 
BMbM —black o& 
BMbm —black @ 18 
bM bm —pink @2 13 
F, black *@ BMbM 
Pink @ bM bm 
" BMbM —black & 24 
bM bM —pink o 21 
BMbm —black @ 5 
bM bm —pink @ 19 
Pink of bM bM 
F, black 9° BMbm 
bM BM—black ” 4 
> bM bi == pinks Cea 
It will be seen that all the above crosses give the typical 
Abraxas results if B and M be assumed to be completely cou- 
pled,‘ but I have purposely omitted one cross: 
4 Only in the second and fourth matings is there any opportunity for crossing 
over, and in those two a total of only seventeen birds that would be affected by 
such crossing over. 
