174 Iiiheritance of Coat Colour in Mice 



Pink-eyed yellow x chocolate-lilac ; 



Pink-eyed Blue Chocolate- 

 yellow lilac lilac Champagne 



8 2 8 8 observed 



10-4 2-6 5-2 2-6 calculated 



Pink-eyed yellow x champagne : 



Pink-eyed Chocolate- 



yellow lilac Champagne 



7 4 7 observed 



9-0 4-5 4-5 calculated 



Sable Mice. 



Among the yellow mice I used for my experiments were some 

 individuals, which produced sables when mated with blacks or choco- 

 lates. As these appeared very early in my experiments, I at first 

 concluded that sables would always result from such matings. Subse- 

 quent investigation however showed that the power to produce sables 

 was limited only to certain mice and that it was a hereditary quality. 

 At present I am unable to offer a scheme which correctly represents the 

 relation of sables to the other colours. 



Sable mice are well known to the Fancy. They differ from yellow 

 mice in having a dark black or brown streak down the middle dorsal 

 region while the rest of the mouse is yellow. The streak may be very 

 narrow, when the mouse is said to be a light sable, or very broad when 

 the mouse is a dark sable. As a general rule, the hairs in this dark 

 streak show an agouti pattern, being black or chocolate barred with 

 yellow. But this does not mean that the mouse is carrying agouti 

 determiner. But it is possible to produce sables in which the barring 

 of the dorsal hairs is absent, and at various times I have had black, 

 blue, chocolate and silver fawn mice which differ only from the ordinary 

 forms by having yellow bellies, and which from their genetic behaviour 

 must be classed with the sables. They always moulted subsequently 

 into ordinary sables. 



The appearance of the sable mouse varies very much according to 

 age. During the first few months the marking is very definite, but as 

 age comes on the sable appearance is lost, so that a mouse, which was 

 a very good specimen at three months may be hardly distinguishable 

 from an ordinary yellow mouse at 18 months old. The amount of 

 yellow in its colouring increases with the successive moults. 



Sables are not to be confused with sooty yellow mice, which result 

 from mating ordinary yellows with blacks or chocolates. The sooty 

 yellow is a dirty colour all over and never shows a definite pattern. 



