60 THE BOOK OF NATURE STUDY 



patch of black more or less completely encircled by a 

 broad black ring. The stripes down the centre of the back 

 also differ in width and number. Those who are engaged 

 in training the powers of children's observation would do 

 well to set their charges to work in collecting notes on the 

 cats they meet with, in regard to this peculiarity of marking, 

 which is well shown in our illustration. It is curious that 

 no really intermediate conditions occur even when cats have 

 descended from parents of opposite types. Persian cats, 

 owing to the length of hair, do not well show either types of 

 pattern. 



Attention should also be drawn to the different colours of horses 

 bay, brown, chestnut, black, roan " blue " and " strawberry " 

 white and dappled grey ; and it should be pointed out that no 

 wild races show these colours. 



As a rule, the colours of mammals, as of birds, bear a more or 

 less close relation to the surroundings or " environment " in which 

 the creature lives ; the coloration being of such a nature as to 

 cause it to harmonise more or less completely with the ground, or 

 vegetation. Thereby the animal is enabled to escape observation, 

 and thus either to avoid enemies or to secure prey by creeping 

 up unawares. Thus we have "protective resemblances" and 

 " aggressive resemblances," according as they serve for offensive 

 or defensive purposes. And it will further generally be found 

 that the upper part of the body is much darker in colour than 

 the under part. And for this reason. The darker upper parts, 

 being exposed to the light, are rendered lighter and less con- 

 spicuous, while the lighter colour of the under parts destroys the 

 shadow which by the relation of the body to the ground is 

 unavoidable. Thus, by toning down the upper surface and 

 lightening up the under surface, the general effect of solidity is 

 cancelled, and the animal enjoys a measure of invisibility which 

 is truly surprising, as those who have suddenly flushed hares and 

 rabbits know ; for so long as they lie still they are almost invisible. 



But there are some notable and puzzling exceptions to this 

 rule ; though these, being natives of other and far-distant countries, 

 are not generally to be met with save in Zoological Gardens or in 

 a wild state. The curious ratel of Africa may be cited as a case 



