Of the frefh IVater Polype. 1 7 1 
languid ; yet r.everthelefs it requires a confiderable degree 
of cold, to reduce them to a motionlefs ftate, and that 
muft be very near to that of freezing, at which time 
they are more or lefs contracted, and fo remain ; but as 
foon as the water in which they are, acquires fome de¬ 
gree of warmth, they ftretch themfelves out, and move 
proportionably to the heat thereof. It is not neceffary that 
this degree of heat be very confiderable, but is fufficient 
for them, if the water be of a temperate heat, which is 
exa&ly fhewn by the fifty-fecond degree on Farenheidt’s 
thermometer m . 
The arms of the green polypes feldom exceed the 
length of their bodies, as at fig. 331. An inch is com¬ 
monly the length of the arms of the fecond fort, as at 
fig. 332. though fome are longer. The arms of the third 
fort are generally about eight inches, fig. 333. for which 
reafon Mr. Trembley calls them long armed polypes, s 
The polype can extend and contraCl its arms, without 
extending or contracting its body; and its body, with-r 
out any alteration in the arms; it can alfo extend and 
contraCl all or fome of its arms, independant of the 
others. 
Its body and arms are alfo capable of bending in all 
poffible directions, fome of which are reprefented by fig. 
337. in which attitude they are fometimes found ; the 
body and arms can alfo twift themfelves, as at fig. 338. 
and 334* It is likewife remarkable, that the arms of the 
fecond and third forts of polypes, generally bend at fome 
diftance from their joining to the body. 
The 
m Farenheidt’s Thermometers, as well as thofe of Sir Ifaac 
Newton, Mr. Reaumeur, D’Lifle, and others may be had at 
my fhop, made after the belt manner, and graduated from 
actual experiments; at Tycho Brahe 1 ? head. No. 60. in Fleet- 
ftreet, London. 
