SOME STRANGE NURSING HABITS 



While the instinct of taking care of their progeny, whether 

 these are born in the hving stage or first come into the 

 world in the form of eggs, is more or less deeply 

 implanted in the higher vertebrates, among the lower 

 members of that great group the eggs and young are 

 very frequently left to shift for themselves. Still this 

 state of things is by no means universally the case ; and 

 I shall show in the course of the present article that 

 certain amphibians and fishes exhibit structural modifica- 

 tions for the purpose of protecting their eggs and young, 

 which are almost or quite unparalleled elsewhere. Cele- 

 brated as they mostly are on account of their highly 

 developed parental instincts, birds exhibit no instances 

 where the body of either parent is specially modified 

 for the purpose of carrying about either the young or 

 the eggs after their extrusion. And I believe that the 

 same holds good with regard to reptiles, although into 

 the disputed question whether vipers afford protection to 

 their young by allowing them to run down their throats 

 I am not going to enter here, beyond confessing that I 

 am inclined to trust the numerous observers who state 

 that they have seen the phenomenon with their own eyes. 

 With certain groups of mammals — notably the marsupials 

 — the case is, however, different, many of them, like the 

 kangaroos, carrying their imperfectly developed young in 



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