Of the frejh Water Polype. 189 
Neverthelefs this combat ends more happily than we can 
at firft believe, in behalf of the devoured polype j for the 
other gets the prey entirely out of its ftomach, and the 
devour’d one comes forth again found and fafe from the 
body of its enemy, after having been detain’d there -above 
an hour. 
Polypes can eat a great deal at a time, and they can 
/aft a great while ; and they void their excrements at their 
mouth. 
After a worm is /wallowed, the tranfparency of the 
polype’s (kin will permit us to fee it diftinctly, as at fig. 
379. the worm gradually lofes its form, and is at firft ma¬ 
cerated in the ftomach of the polype, the juice nourifhes, 
and being feparated, the remains thereof are thrown out 
at the mouth, as at fig. 381. 
It is alfo obfervable, that their aliments are pufhed 
backwards and forwards, from one extremity of the fto¬ 
mach to the other, which contributes much to its di- 
geftion ; which motion may be feen in the microfcope, if 
you choofe a polype that is not too full. This kind of 
periftaltic motion fpreads the nouriftiing juice all over 
the ftomach. But for an obfervation of this kind, it is 
beft to feed the polypes with fuch aliments as can beftow 
a lively colour’d juice ; for example, thofe worms whofe 
intcftines are full of a red matter, for by this means we 
may fee, that this alimental moifture is conveyed not only 
to the extremity of the body, but alfo into its arms; 
whence it is plain, that a polype’s arms are perforated,- 
each of them forming a kind of gut, which communicates 
with that of the body. 
1 his was confirmed by examining a polype, which 
had lucked the red matter contained in the inteftines of a 
flat worm, fig. 383. Its body is of a tranfparent white/ 
and intcftines extreamly vifible, and of a crimfon red; 
care 
