46 THE POLYPI. $ 87. 
Polyps are placed in direct intereommunication. It is not rare to find 
this general cavity divided into chambers by mesenteric membranes stretch- 
ing longitudinally from it to the external surface of the stomach. 
The base of the stomach of many, and perhaps all of the Anthozoa, is 
pierced by one or more valvular openings, which communicate with the 
cavity of the body.” These animals, by controlling at will these orifices, 
can allow to pass into the cavity of the body the proper materials, which 
are probably water and liquid chyle.” This digestive apparatus thus com- 
municating with the cavity of the body, reminds one of the organization 
of the Infusoria. 
The cavity of the stomach is lined by very delicate ciliated epithelium, 
which is continuous through the orifices upon every surface of the cavity 
of the body and arms, and even into the intercommunicating canals of the 
corallum. 
The color of the walls of the stomach is quite varied, and is due to cer- 
tain pigment cells which very probably perform the function of a liver; 
for these animals are entirely wanting in any other glandular appendix of 
the alimentary canal, analogous to a liver.® 
4 There are often eight of these longitudinal 
hambers, as in Veretillum, Alcyonium and Al- 
cyonidium (see Icones zoot. Tab. XXXIV. fig. 25 
also Ann. a. Sc. Nat. IV. 1835, pl. XVI. fig. 3, and 
pl. XII. fig. 3, 4). In Actinza there are seven 
more. With Edwardsia the eighth mesenteric di- 
visions do not reach the sides of the body (Qua- 
trefages loc. cit. pl. I. fig. 2).* 
5 These orifices were long ago observed by the 
elder anatomists upon various Polyps. After- 
wards their existence was incorrectly doubted by 
other naturalists ; for lately they have been dis- 
tinctly made out. Thus, in Veretillum cynomo- 
rium (Rapp, Nov. Act. physico-medica XIV. 1829, 
p- 650), in Alcyonidium and Alcyonium (Milne 
Edwards, Aun. d. Se. Nat. LV. p. 325, pl. XV. fig. 
6), and in Edwardsia (Quatrefages Ann. d. Sc. 
Nat. XVIII. p. 91). 
In Sertularia and Campanularia there are 
openings between the stomach and the tubulous 
cavities of the corallum (Lister, Phil. Trans. 1834, 
p. 371, and Van Beneden, Mim. sur les Campanu- 
laires, loc. cit. p. 17). There must be direct com- 
munication of this kind with the Actiniae, since 
they regularly reject hy their mouth nettling fila- 
ments, from the chambers of their body. With 
Hydra, the stomach communicates, by an orifice 
situated at its base, with the narrow tubtlous cavity 
of its cylindrical foot. But at the extremity of this 
tube there is no oval opening, and the tube itself can- 
not be regarded as a rectum, for it receives neither 
feeces, nor fragments of food, and is not affected by 
the frequent enormous dilatations of these animals 
from surfeit. Corda therefore is incorrect in as- 
signing an anus to these animals. (Nov. Act. phys- 
ico-mediea XVIII. p. 302, Tab. XIV. fig. 2, E.) He 
appears to have entirely neglected the foot of this 
animal, which, however, has been well figured by 
Ehrenberg (Abhandl. d. Berl. Akad. 1836, p. 134, 
Taf. II. fig. 1); and since Roesel (Insektenbel. III. 
Taf. LXXVII. and LXXIX. fig. 2, and LXXXVI. 
LX XXVIII. fig. 6) has perceived it in all unmuti- 
lated arm-polyps. Sars (Faun. littoral. Norveg, p. 
* [§ 37, note 4.] With all the Actinaria the Jam- 
eli of the visceral cavity are the multiples of 
six ; all the Alcyonaria have eight of these lamella. 
Bee Dana loc. cit. p. 49. — Ep. 
t[§ 37, note 5.] With the Actinoidea, recent 
rescarches have shown that the stomach communi- 
21) has found with a Lucernaria a stomach opening 
inferiorly, and communicating directly with the 
cavity of the body. This communication has been 
observed also by Frey and Leuckart (Beitr. p. 
3) with the Actiniae and several other Anthozoa.t 
6 Quatrefages (Ann. d. Sc. Nat. XVII. p. 87, 
91) has seen the stomach of Edwardsia entirely 
filled with Spirorbis, and other solid food, without 
any of it passing into the cavity of the body. 
7 With Infusoria, the lower end of the cesophagus 
is free, so‘that the food passes directly from it into 
the parenchyma of the body, where it forms a cav- 
ity ; but with the Anthozoa, there is a stomach, 
from which chyle alone can pass into the cavity of 
the body. 
8 Tnese cells are white in Edwardsia, yellow in 
Alcyonidium and Alcyonium, and brown in Vere- 
tillum and Hydra. In the last, the brown is dis- 
tinctly due to irregular pigment granules of that 
color, floating in the clear liquid of the cell. Prob- 
ably these cells, by bursting, empty their contents 
into the stomach ; at least, I have been able to find 
no excretory duct, such as Corda has figured with 
the Hydra fusca (Nov. Act. Acad. physico-medica 
XVIII. p. 302, Tab. XV. fig. 15—17; or Ann. d. 
Be. Nat. VIII. p. 366, pl. XIX. fig. 15—17). 
In Hydra viridis, these brown cells of the stom- 
ach can easily be distinguished from the layer of 
green pigment belonging to the parenchyma of the 
body. Moreover, if a transverse section of this 
animal is made, there appears a wide difference of 
organization between the internal and external sur- 
face of the stomach; the first has ciliated epithe- 
lium and hepatic cells, the second a bare skin with 
prehensile organs. This being so, how can these 
animals be everted like the finger of a glove, as some 
naturalists have affirmed, and yet live ? for the two 
surfaces of the stomach, so different, could not re- 
place each other, and then again the cavities of the 
arms would open directly outward. Indeed, it is 
not possible to return unmutilated an everted 
Polyp, since the inextensible cavity of its foot can- 
not leave the body with impunity. The gastric 
eates with the cavity of the body by a single ori- 
fice only, which may be closed by muscles. Sce 
Dana, loc. cit. p. 40, 44, pl. XXX. fig. 3, a, b, c, d- 
It has been since verified by Cobbold, Aun. Nat. 
Hist. XI. 1853, p. 121, with figures. — Ep, 
