The Fresh-Water Polypi. 605 
the same water ; and feed on the various species of small 
worms and other aquatic animals within their reach. 
When any of these pass near a Polyp, the latter sud- 
denly catches it with its arms, and dragging it to its 
mouth, swallows it by degrees, much in the same man- 
ner as a snake gorges its prey. Two Polypi may 
occasionally be seen in the act of seizing the same worm 
at different ends, and dragging it in opposite directions 
with great force. It sometimes happens, that while one 
is swallowing the end it has seized, the other is employed 
in the same manner ; and thus they continue swallow- 
ing, each his part, until their mouths meet. They then 
rest for some time in this situation, till the worm breaks 
between them, and each goes off with his share. But 
sometimes when the mouths of both are thus joined 
together a combat ensues, and the largest Polyp usually 
swallows his antagonist; the animal thus swallowed, 
however, seems to be a gainer by its misfortune, as after 
it has lain in the conqueror's body for about an hour it 
issues unhurt, and often in possession of the prey that 
had been the original cause of contention. The remains 
of the animal, on which the Polyp feeds, are evacuated 
at the mouth, the only opening in the body. The species 
are multiplied by a kind of vegetation, one or two, or 
even more young ones, emerging gradually from the sides 
of the parent animal ; and these young ones are fre- 
quently again prolific before they drop off; so that it is 
no uncommon thing to see two or three generations at 
once on the same Polyp. But the most astonishing fact 
respecting this animal is, that if a Polyp be cut in 
pieces, it is not destroyed, but is multiplied by dissection. 
It may be cut in every direction that fancy can suggest, 
and even into very minute divisions, and not only the 
parent stock will remain uninjured, but every section 
will become an animal. Even when turned inside out, 
it suffers no material injury ; for, in that state it will 
soon begin to take food, and to perform all its other 
natural functions. 
M. Trembley, of Geneva, ascertained that different 
portions of one Polyp could be engrafted on another. 
Two transverse sections brought into contact will quickly 
