THE DRAMA OF LIFE 37 



The theory is that those in the second set can afEord to call 

 attention to themselves, being unpalatable or in some 

 other way safe. To prove a theory of this sort is impossible, 

 but it becomes cogent and convincing in proportion to the 

 number and variety of cases to which it can be apphed. 



Mr. Pocock, of the Zoological Society's Gardens in London, 

 has apphed the theory to various Manmials, and it seems 

 to work out well. Taking the common shrew (Sorex vulgaris), 

 for instance, he points out that it is fearless and careless, 



Fig. 14. — ^The rattle of the rattlesnake (Crotalus'), composed of a number 

 of homy bells, added to at successive moults. It is agitated 

 when the snake is excited and produces a shrill noise. Thus large 

 animals, on whom the snake would simply waste its poison, are 

 warned o£E. 



and that it makes a frequent squeaking as it hunts. It 

 can afEord to be a self-advertising animal because of a 

 strong musky scent, which makes it unpalatable. A cat 

 will never eat a shrew. The odoriferous glands are situated 

 in a long Une on each side of the body. Similarly, the large 

 Indian musk-shrew (Crocidura coerulea) is conspicuous even 

 at dusk, quite fearless in its habits, and goes about making 

 a pecuhar noise like the jinghng of money. But it is safe in 

 its unpleasant musky odour. 



The common hedgehog is comparatively easy to see at 

 night ; it is easy to catch, because it stops to roll itself up, 

 on very shght provocation sometimes ; it rustles about in 



