178 Of the frejh Water Polype. 
before. The grains fall off from all fides, it contracts 
Itfelf, the body and arms fwell and lofe their fhining 
whitenefs, and at laft their form, as at a, fig. 348. and 
nothing is to be found in its place but an heap of grains 
as at b. 
The ftruClure of the polype’s arms bears a near refem- 
blance to that of its body; and when obferved with the 
microfcope, we find their exterior furface to appear lha- 
greened alfo, fig. 362, an arm much contracted appears 
extremely fo, and even much more fo than the polype’s 
body. 
If a fufpended arm that extends itfelf be obferved, the 
grains may be feen a little afunder, which when con¬ 
tracted almoft touch, but fo that intervals are left be¬ 
tween them, as at fig. 363. When at a certain degree 
of extenfion, its furface feems only to be ftrewed with 
pimples as at fig. 364. which continue ftill to feparate, as 
the arms extend, and are at laft placed upon a thread 
e e e, fig. 365. Thefe pimples are formed by the re¬ 
union of many grains, and at the firft glance appear like 
a firing of beads, fig. 365. 
The different ftates of a polype’s arm, may be obferved 
at the fame time, in the fame arm, but at different places 
thereof, by calling the eye, armed with a microfcope, 
from one end of the arm to the other, and efpecially if 
the feveral portions thereof be carefully obferved with a 
large magnifier, they will appear as at fig. 363. which 
reprefents that part of the arm ftretched out, which is 
near the polype’s head, the grains thereof being but little 
feparated, but are farther afunder in fig. 364. which is 
about the middle of the arm; and fig. 365. Ihews the : 
grains as if they were ftrung upon a thread, as they are 
feen upon the extremity of a polype’s arm. 
This i 
