f 92 
i ' f! V 
further confirmation of these views, it may be bri f ^ 
noticed, that if the cells be placed in acetic or d't' 1 
nitrons acid, all the carbonate of lime is removed, arK 
undoubted organic portion of the cells looks but sli? ^ 
altered from what the cells were before the obliterai 
took place. If the experiment, be reversed and a sp e jg 
men be boiled in caustic potash, the organic matter . 
removed and the spongy calcareous case remains P e . rtor ‘ f f , 
or porous from the removal of the matter which . 
merly pervaded the whole. Thus then it seems clear 
the polypidoms are organic.* . i o9 1, 
The mode of reproduction in this order varies a grea 
and in many genera it is entirely unknown. In the gt jt 
Crisia, which we have noticed as resembling Sertnlar > ^ 
is effected by the periodic formation of ovarian vesicles- 
the formation of these cells is very similar to that oi •,) 
described among the Hydroidce, little need now ° ^ 
on the snbject. Tn them the ova or gemmules are lorraeii 
the vital pulp, which at first occupies the whole of the c* (1)fl 
but as develop e went advances, it is withdrawn to wai- «• j, 
centre. It. is of the same consistency as the pulp ^ , g 9 
iot® 
br 3 ' 
lb« 
centre. J * \$ 
traverses the centre of the polypidom, and in I. 
continuation of it. It very soon becomes developed 
globular gemmules, which are clothed with numerous 
tory cilia, that arc in constant action.. By these, at t j 
cemntnles have escaped from the vesicle, they are " 'fluitl' 
about in a rotatory manner through the surrounding ! ' A* 
like worlds in minature. Like ihe gemmules of the Hyw 
they at last become fixed, and like them spring up into , 
cate and beautiful arboresence; but they are cal °‘ ipP s, 
instead of horny. After having performed their funci.^ 
these organs drop off and disappear or are thrown oi ^ 
the leaves of trees in autumn. In the Ihjdroidm t b > (0 - 
noticed, that these temporary organs are abnndan 3 J ,11 
duced, and may, in one or other species be nea r t0 
seasons of the year; here, on the contrary, they PP| )( j5i 
bo of rare occurrence, for after long and attentive e „ 
two specimens only have been procured. This P' 3 (i>' 
vesicles, however, may arise from the solid, calcareo -*^ r y 
friable nature of the structure; for as they stand o ^ 
slender foot-stalks, they must be incapable of «*«« » t H« 
violence of the sea. This however can liardiy e$e H 
onl v reason, since many hundreds of specimen 
species, have been examined at different seasons, in s 
and after long continued calm weather, with 
* This subject is further elucidated by M. Mhnc Edwaids, 
Sciences Nat., vol. 1, p. 25. Johnston’s Brit. Zoopn.j p- 
