AND THE LOWER ANIMALS. 239 



Thus, all agamic reproduction is associated with 

 groivth, properly so called. 



This conclusion, arrived at by a process of reason- 

 ing, is not unsupported by facts. When we amputate 

 an earth-worm's head, or a lizard's tail, what first 

 appears on the circular wound resulting from the 

 operation ? A small tubercle, an actual bud, in which 

 we cannot at first detect either nerves, bones, muscles, 

 or blood-vessels.* This bud increases in size, and, 

 after a while, the various organic elements reappear; 

 the animal reproduces the parts which had been 

 destroyed. This is the first stage of reproduction by 

 bulbs. The hydra, each of whose parts, when it has 

 been divided, will reproduce a perfect animal, pos- 

 sesses this faculty in its highest degree. Bach frag- 

 ment, in modifying the accidental form resulting from 

 the operation, has had to bud in every direction, that 

 is to say, it has had to grow. 



That is what experience teaches us. Mere ordinary 

 observation leads us to the same result; it is even, 

 perhaps, more demonstrative. When treating of trans- 

 formation and metamorphosis properly so called, we 

 showed how the normal growth of animals took place. 

 We saw that this phenomenon was in some instances 

 manifested in the increase in volume, and in others, in 

 the multiplication of the same parts of the body ; and 

 in the latter case it frequently happens that the super- 

 added part presents a series of organs, which almost 

 constitute it a separate individual. For example, in 



* I have made several experiments, especially upon the first of 

 these animals, but I postpone their publication till I have com- 

 pleted them. I may, perhaps, bring out this work at some future 

 period. 



