Ir THE SERVICE OF TAILS 93 
“As regards the white tip of the tail of certain 
mammals, there are some curious phenomena 
connected with tips... . White and black are 
interchangeable. 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 dress is brown with black 
tips to his ears; and the ermine is also brown with 
half the tip end of the 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.” 
These peculiarities of color may be correlated 
with the fact that the tips of ears, occasionally, and 
the tips of tails, very frequently, are adorned with 
tufts of hair, in the case of animals not otherwise 
long-furred. That is the case with all the hoofed 
beasts that have long tails, as the horses and asses, 
cattle, camels, giraffe, and several of the South 
African antelopes; the practical service of this as 
a wisp to drive away biting insects is recognized by 
every one; and it results in the ability of such ani- 
mals to stay on the plains all summer, while their 
short-tailed relatives are obliged to migrate to moun- 
tain-tops and other regions of sometimes poorer 
pasturage in order to escape the flies. 
This phenomenon of marked color and increased 
hairiness at “tips’’ may be further correlated with 
the fact that in the tip of the tail, particularly, 
seems to be centred or focalized, an unusual de- 
