REI'RODUCTION. 527 



The Asterias, the Actinia^ and some of the lower 

 species of Annelida, as the Nais, are also capable 

 of being multiplied by artificial divisions ; each 

 segment having the power of supplying others, and 

 containing within itself a kind of separate and 

 individual vitality. 



A power of more partial regeneration of muti- 

 lated parts by new growths, which is very analogous 

 to that of complete reproduction, exists in the higher 

 orders of animals, though it does not extend to the 

 entire formation of two individuals out of one. The 

 claws, the feet, and the antennae of the Crustacea, 

 and the limbs of the Arachuida, are restored, when 

 lost, by a fresh growth of these organs. If the 

 head of a Snail be amputated, the whole of that 

 part of the animal, including the telescopic eyes, 

 and other organs of sense, will be reproduced. 

 Even among the Vertebrata we find instances of 

 these renovations of mutilated parts; as happens 

 with respect to the fins of fishes : for Broussonet 

 found that in whatever direction they are cut, the 

 edges easily unite ; and the rays themselves are 

 reproduced, provided the smallest part of their base 

 has been left. The tails of Newts, and of some 

 species of Lizards, will grow again, if lost; and 

 what is more remarkable, the eyes themselves, with 

 all their complex apparatus of coats and humours, 

 will, if removed, be replaced by the growth of new 

 eyes as perfect as the former. We have seen that 

 the teeth of Sharks, and other fishes, are renewed 

 with the utmost facility, when by accident they 

 have been lost. Among Mammalia, similar powers 

 exist, although they are restricted within much 

 narrower limits ; as is exemplified in the formation 

 of new bones, replacing those which have perished. 



