14 ANIMAL PARASITES AND MESSMATES. 



these creatures, and has clearly shown how interesting 

 they are, not only to naturalists, but to people in 

 general. 



Crustaceans and worms furnish the greatest number 

 of paupers and infirm individuals ; and a great many of 

 them need the continual assistance of their neighbours 

 to enable them to get their living. While other animals 

 advance towards perfection as they grow older, it is far 

 different with many crustaceans, and we should be 

 tempted to refer to the vegetable kingdom many of them 

 at the very period when they are approaching the adult 

 condition. Cuvier placed all the class of cirrhipedes 

 among the moUusca, and the lernseans among the 

 worms. Many of these animals which are but indif- 

 ferently adapted to live without help from others, have 

 recourse to benevolent neighbours ; from one they seek 

 only shelter, from another a part of his booty, from 

 a third both an asylum and protection. They are often 

 reduced to a mere skin; everything else has disappeared, 

 and there remains no proper organ except that which is 

 necessary for the reproduction of the species. Corpulent, 

 blind, impotent, legless cripples, their existence is more 

 precarious than that of those miserable mutilated beings 

 found in our cities ; they only live on the blood of the 

 neighbour which gives them an asylum. Yet when they 

 first quit the egg they are all free; they frisk, they swim 

 with the rapidity of lightning, and at the close of life 

 we find them deformed, and crouched in some living 

 refuge, as if a foul leprosy had atrophied within them all 

 the organs which served as a means of communication 

 with the outer world. Parasites and messmates, fur- 

 nished at first with the same kind of limbs and the 



