12 THE FLEA [CH. 



indigenous to the New World are distantly related 

 to those of the Old World. Broadly speaking the 

 geographical distribution of the parasite must follow 

 that of the host. But sometimes the parasite is 

 impatient of cold and cannot follow the host out 

 of the tropics. The chigoes and their allies are fleas 

 of hot countries. Different kinds of bats are found 

 from the tropics to the Arctic circle, but the same 

 bat-fleas are not found everywhere. 



When a flea has a cosmopolitan range it is 

 probable that it has travelled over the world in 

 company with its host. 



Monkeys have no fleas. This is an assertion that 

 is commonly received with surprise and incredulity. 

 Occasionally a gorilla or a chimpanzee may get a 

 chigoe in its toe. And monkeys in zoological gardens 

 or menageries are possibly exposed to the danger 

 of catching an occasional human flea from the people 

 who crowd round their cages. These are remote 

 contingencies which may happen to anyone. Healthy 

 wild monkeys are much too clean and active to 

 harbour fleas. When they search one another's fur 

 in a fashion that must be familiar to most persons, 

 they are clearing their coats of particles of scurf or 

 of similar scraps of dirt and not of fleas. So, 

 speaking generally, it may be said that no fleas have 

 been found truly parasitic on monkeys. 



Bats have fleas, but not in great abundance. All 



