612 
FRESH-WATER POLYPE. 
was some time before M. Trembley could satisfy 
himself of its real nature. 
In the description of this species may be included 
two others, the green and the gray polype ; both 
of which, like the brown, are common either in 
ditches, ponds, or slow-running streams. These 
diminutive objects may be found, in the spring, ad- 
hering to all sorts of aquatic plants, and to any loose 
substance that may be lying in the water. When 
first taken up they appear like a small dot of trans- 
parent jelly, and would be rejected, by those not 
aware of their curious conformation, as the exuviae 
of some fresh-water insect. One of their most 
common haunts is under the leaves of duck-weed, 
which can hardly be taken up in any quantity, in 
the spring of the year, without some of these ani- 
mals adhering to it. After the water which con- 
tains them has been at rest for a short time, these 
little lumps of jelly will be seen gradually to ex- 
pand, and take the form of a stalk, from the top 
of which eight slender filaments (if this species is 
examined) will make their appearance and arrange 
themselves round the centre, where the mouth is 
situated. In this form it looks so like a vegetable, 
that Trembley, in a letter written to M. Bonnet in 
January 1741 , says, “ I have studied it ever since 
June last, and have found in it striking character- 
istics of both plant and animal. It is a little aquatic 
being. At first sight every one imagines it to be a 
plant ; but if it be a plant, it is sensitive and am- 
