POLYPES. 



56 



animals are formed. If one of these be cut into three, 

 four, or half-a-dozen pieces, each piece supplies the want- 

 ing parts, and so many animals are made, all as perfect 

 and active, and endowed with the same functions, as the 

 first. Nor does it signify in what direction the mutila- 

 tion is made ; a longitudinal, a diagonal, or a transverse 

 division is equally successful ; nay, even a small portion 

 of the skin soon grows into a polype. 



It was from this power of perpetual reproduction, that 

 this singular animal received the name of Hydra, by 

 which it is known among naturalists ; as if it realised the 

 ancient monster of fabulous story, whose heads sprouted 

 anew as fast as they were cut off by Hercules. 



Most curious monstrosities were produced by the expe- 

 riments of philosophers on these animals, especially by 

 partial separations. If a polype be slit from the summit 

 to the middle, one will be formed having two heads, each 

 of which will capture and swallow food. If these again 

 be slit half-a-dozen times, as many heads will be formed 

 surmounting the same body. If now all these be cut off, 

 as many new ones will spring up in their place, while 

 each of the severed heads becomes a new polype, capable 

 of being, in its turn, varied and multiplied ad infinitum ; — 

 so that in every respect our little reality exceeds its fabu- 

 lous namesake. 



The polypes may be grafted together. If cut-off pieces 

 be placed in contact, and pushed together with a gentle 

 force, they will unite and form a single one. The head 

 of one may be thus planted on the trunk of another. 



Another method of uniting them, perhaps still more 

 wonderful, is by introducing one within the other ; the 



