Of the frejh Water Polype. 183 
from that of its extenfion, fig. 367. As the food digefts, 
and it voids that which does not ferve for nourifhment, 
its body lengthens, and gradually recovers its natural 
form. 
Mr. Trembley finding thefe millepedes a proper food 
for the polypes, he collected a great quantity of them, to 
feed thofe he kept in glafies, and found them in fwarms 
at the Tides of ditches, creeping on plants, and all other 
bodies that were in the water. 
Alfo on obferving how voracioufiy the polypes eat 
thefe millipedes, he imagined it was not the only agree¬ 
able food to them, and was therefore defirous of finding; 
out other animals to nourilh them withal, befides the 
trouble of getting a fufficient quantity of millipedes from 
other places took up too much time ; upon which he 
opened a polype that was taken out of the water, with 
its belly full of food; from whence came out little in¬ 
fers, which he calls pucerons or fleas, and amongfl 
thefe another fort that multiply extremely, and are often 
eafdy to be procured in great quantities; fee the fig. 
marked p, at the end of one of the arms, fig. 367. which 
reprefents one of thefe fleas of its natural fize, and as it 
appeared in the microfcope at fig. 361. They are exa&ly 
defcribed by Swammerdam 0 , and are remarkable for 
two branching arms, which proceed from their head, 
which ferve them inftead of fins. The arms inclined 
Swammerdam to call them by the name of puceron 
branchus; they are continually fkipping about the water, 
and are generally fomewhat reddilh. 
On putting fome of thefe pucerons into a glafs with 
polypes, they prefently feized on fome of them, and 
began to extend their mouths, fidt in the form of a 
N 4 concave, 
® Swammerdam’s Hift. de Infeft, p, 86, Edit, de Leid. 1737, 
