i86 STUDIES IN THE EVOLUTION OF ANIMALS 



doubt that these two marks are inherited from the Wolf. When 

 in India, I examined a large number of very young Wolf-cubs, 

 which had their eyes still closed. They were usually of a dark 

 chocolate colour, and a large proportion of them had a white mark 

 on their chests, and a white tip to their tails. Probably in the 

 Wolf-cubs these are only vestiges — remnants, as I said — of a more 

 extended light-coloured under surface. For, as the Wolf-cubs grow, 

 the white becomes blended with the general fawn or tan colour of 

 the under surface, and eventually totally disappears, while the dark 

 colour of the back turns into an intimate mixture of black and tan 

 resembling that of certain Collies whose black upper surface had 

 changed into a mixture of black and tan. 



As regards the white tip of the tail of certain mammals, there 

 are some curious phenomena connected with tips — tips of tails, 

 tips of ears, and tips of feet — which would point to some difference 

 in the innervation of tips. As I said, white and black are inter- 

 changeable. There are many mammals which have black tips to 

 their tails, and this, in allied or other individuals, may change to 

 white. The Arctic Hare in its summer clothing is brown, with black 

 tips to its ears ; and the ermine is also brown with half the tip end 

 of its tail black. When these two animals get their snow-white 

 winter clothing, the tips of the ears of the one, and the tip of the 

 tail of the other, remain black ! I have seen a number of skins of 

 the Arctic Fox in the furriers' shops, and many of them had a tuft 

 of black hairs on the tips of their tails. There are two coloured 

 pictures of the red common Fox in the Royal Natural History. 

 One has a black tip to its tail, and the other a white tip. 



In this connection I would note a curious mark I have seen on 

 two sister Cats of the tabby variety ; (a) had pale tan hands and 

 feet, and on the hind limbs, from the heel to the toes, the back sur- 

 face was black ; while {b) had white hands and feet, and only a 



