F. M. Durham 175 



I have never bred a homozygous sable mouse. Bred together, 

 sables may throw sables, yellows, blacks, chocolates, and also agouti, if 

 they are carrying the agouti determiner. 



Yellows carr3dng the sable determiner mated together will throw 

 sables, and sables mated together may throw yellows. By mating 

 together yellows carrying sable I have obtained 



111 yellows, 38 sables, and 69 other coloured mice. 

 By mating yellows carrying sable with other coloured mice, not 

 yellows, I have obtained 



78 yellows, 5.5 sables, and 80 other coloured mice. 

 Mating together sables, I have obtained 



161 sables, 43 yellows, and 142 other coloured mice. 

 Mating sables with other colours, not yellow, I have obtained 

 93 sables, 90 yellows, and 174 other coloured mice. 



Examination of the records suggests, that there is more than one 

 sort of sable mouse, and that it is possible to produce sables which 

 never throw yellows at all. 



Thus I had as a result of 5 matings between blue sables, 29 blue 

 sables, and 23 blue mice, and no yellows at all. 



4 matings between blue sables and dark sables gave 

 16 sables and 8 other colours (no yellows). 



7 matings between blue sables and blue gave 

 20 blue sables and 19 blues. 



On examination of the results produced by mating sables together, 

 I find that the matings in which yellows were produced, the offspring 

 consist of 62 sables, 43 yellows and 64 other colours, while the offspring 

 of the matings in which no yellows were produced, consist of 99 sables 

 and 78 other colours, suggesting a 9 to 7 ratio. 



The matiuors of sable x other colour show that the families iu 

 which yellow appeared consisted of 



48 sables, 90 yellows, and 107 other colours, 



in the remaining families there were 45 sables and 67 other colours. 

 Matings between sables and yellow^s .without the sable determiner 



give 



23 yellows and 18 other coloured mice, no sables. 



Matings between yellows canying sables with sables give 



14 yellows, 28 sables and 17 other coloured mice. 



