3 
P°'.Vpe depends on the colour of the food, and that, those 
fannies which are nearest the gastric surface are the first 
0 change and so in gradation from the stomach to the 
^Sternal surface.* There appears to he no anatomical dif- 
e fence between the granules of one part of the body and 
pother; for if the animal be turned inside out, the outside 
"'l* perform the function of digestion as perfectly as the 
anginal gastric surface, and the young will frequently sprout 
r °m the tentacula as well as from other parts of the body. 
. The horny or sheathed Genera vary a great deal in form, 
e Dsity, and the elaboration of their various parts, and have 
very graceful appearence. Their form is more or less 
rooreseent, and through their centres runs a granular pulp, 
uich terminates, at the extremities of the branches, in 
ptypes, which are modifications pf the pulp and formed 
rottl it. In the Hermia the sheath is nearly rudimentary, 
pl'l ^ 0rms an imperfect covering for the upper part of the 
Hi 
P; in the Tubularia the polypes always protrude beyond 
•rlularite. 
tubes, which cover the pulp ; in the I'/ioie, Serli 
: v toularice , Campanularice, Sfc. the polypes are furnished 
cells, into which they retire either from satiety, alarm, 
I r for rest. j n sonie t| le cells are sessile, in others on ringed 
0 °tsulks ; they are cup shaped and arranged in one or two 
VVs on the stems or branches. At certain seasons of the 
more especially about summer and autumn, hut difl'er- 
?. lu dilferent species, there are other larger cells formed, 
>tia 
© 
t*h 
'ch are the ovarian vesicles, which drop olf as soon as the 
a °r ffemmules are perfected. 
The mode of reproduction varies, not only in the different 
ler a, but in the same under dilferent circumstances. Ia 
p ® caked Hydroida the young sprout from the sides of the 
of * as perfectly formed animals, exercising the functions 
’ji, '^dependent life, even before they become separated. 
t|j le Joung after remaining attached for some time, arc 
li l r ° w n off by a vital process and the cicatrix becomes oh- 
to L at , ed ; so that no point can he observed on the old polype 
of lQ dicate the former situation of the young. This form 
y ^production sometimes lakes place so rapidly, that the 
• n g even to the third or fourth generation have young 
Hof 6 t * Je ® rst * s se P arate d from l l le parent; this gives the 
e a very grotesquely branched appearance. 
» hi ® *be Sertulariadcc external ovarian vesicles are formed, 
c “ contain the reproductive gemmules. These are 
v °l. o mb| y> Hist, des polypes p. 132. Roget’s Bridgwater Treatise, 
’ P- 77 and 78. Mag. of Zool. and Bot., vol. 1, p, ”3j. ISote *. 
