POLYPES. 
55 
animals are formed. If one of these be out into three, 
four, or half-a-dozen pieces, each piece supplies the want- 
ing parts, and so many animals are made, all as perfect 
a nd 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 bo grafted together. If cut-off pieces 
be placed in contact, and pushed together with a gentle 
orce, they will unite and form a single one. The head 
o 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 
