VI 



Recent Advances in Animal Breeding and their 

 Bearing on our Knowledge of Heredity 



{Reprinted from the Report of the Royal Horticultural Society's 

 Third International Conference on Genetics, 1906, by 

 permission of the President and Council) 



Curious results are obtained by crossing albino with the 

 so-called Japanese waltzing mice. It is perhaps not neces- 

 sary to say that an albino mouse is one mth an absolutely 

 white coat and with pink eyes, the pink colour in them being 

 due, not to a special pigment, but to the colour of the blood 

 in the vessels at the back of the eye. 



The colour of the waltzing mice used in this experiment 

 is best described by saying that were it not for a patch of 

 fawn on the shoulders, and sometimes on the rump, they 

 would be albinos. Their curious movements, inaccurately 

 denoted by the term " waltzing," are not hkely to be 

 forgotten by those who have seen them. The animals 

 appear to have no control of the movements of their heads, 

 nor of the direction in which they themselves proceed ; 

 and when they are awake, they spend most of their time in 

 twirling round and round, apparently mad, in a very small 

 circle. 



When these two are mated the result is a mouse hardly 

 distinguishable from our common house mouse (when the 

 albino parent is pure bred). 



The hybrid, therefore, has a grey-brown coat and coal- 

 black eves. 



207 



