43 °- 
THE POLYPI. 
$$ 40, 42. 
§ 40. 
All Anthozoa and Bryozoa have a proper circulation; for there rises 
and falls in the cavity of their body a liquid, which is usually clear, and 
often contains round and colorless corpuscles. 
a 
This rises even to the end 
of the cavity of the tentacles, and then returns into that of the body 
generally. In the colonial Polyps, these currents, by traversing the canals: 
of the corallum, thereby pass from one animal to another. 
This movement. 
is caused by ciliated epithelium, which, as we have just seen, lines all the 
cavities of these animals. 
With the Bryozoa, the cavity of whose stomach does not communicate 
with that of the body, these currents are continuous. regular, and have a 
definite direction. 
But with the Anthozoa they are changed by the 
reciprocal action through the stomachic orifices of the liquids of the 
stomach and cavity of the body. These currents are perceived in the 
arms, even when the cavities of these organs open directly into the 
stomach.” 
, § 41. 
Nothing can yet be positively said as to the nature of this circulating liquid. 
for it is still doubtful whether this whole phenomenon should be regarded 
as an aqueous or a sanguineous circulation. 
If we refer to the fact{that the 
Anthozoa can introduce water into the system through the apertures of the- 
stomach, it should be admitted that this system has an aqueous character, 
performing, perhaps, the function of an internal respiratory apparatus, 
er 
given off from the eight principal longitudinal 
vessels numerous lateral branches, which anasto- 
mose frequently in the canals of the corallum, and 
finally form a capillary net-work. The white, 
semi-transparent corpuscles contained in thin 
blood have, according to Will, a diameter of 
about 1-1200 of an inch, and out of the vessels 
have a globular aspect. According to this same 
observer, there is a similar vascular system in 
Actinia.* 
1 The circulation in question has been observed 
by many investigators. Trembley (Mém. pour 
servir a VHistoire des Polyps, p. 219) has per- 
ceived it in Plumatella cristata. Dumortier 
(Mém. sur |’Anat. et la Physiol. des Polypes, p. 47) 
has confirmed this observation. Cavolini (see his 
Memoir on the Anthozoa, p. 56, 87) has seen it in 
the tubes of several Sertularina. There are various 
opinions as to the cause of these currents. Gruit- 
huzsen (Isis. 1828, p. 506) studied them in the 
arms of Hydra, and regarded them due to a com- 
munication with a circular vessel surrounding the 
mouth. But, according to the observations of 
Meyen (Brown’s Miscellaneous Botanical writings, 
IV. p. 490), of Ehrenberg (Mittheil. aus. d. Ver- 
handl. d. Gesellsch. naturf. Freunde z. Berlin, 
1836, p. 27) and myself, the cavities of the arms 
open directly into the stomach. 
The movements of the liquid in the arms of Hydra 
are due not only to the general contractions of the 
body, as Gruithuisen and Meyen have supposed 
but also to the cilia covering these parts. This 
* [§ 39, note 1.] Subsequent researches have 
failed to detect any true circulatory system with the 
real Polyps, and there now can be but little doubt 
that no such system exists. As with the Acalephs, 
was first pointed out by Grant (The new Edinb. 
Phil. Jour. 1827, p. 107; or Outl. of Comp.{Anat. -, 
1841, p. 430), who observed these -curbbnts' ‘in, 
Flustra, Lobularia, Virgulari, fh Pennatula.: 
Nordmann, who has examined this circulation in, ,' 
the body and tentacles of Alpyonedia diaphana,, 
and Plumatella cempanulata, and other Bryozoa,, 
did not find any cilia. He cothpared the currents 
to those seen in the joints of Chara (Microg.. 
Beitrag II. p. 75, or Obser. sur la Faune Pontique,. 
p. 709). I feel positive about the presence of cilia 
in the body of Cristatella mirabilis and Alcyo- 
nella stagnorum. Lister has carefully described 
this circulation with T'ubularia, Sertularia and 
Campanularia; and finding no adequate cause, 
has likened it to that of Chara (Phil. Trans, 1834, 
p. 366, et seq.). Ehrenberg (Abhandl. d. Bert. 
Akad. 1832, p. 299) and Loven (Wiegmann’s 
Arch. 1837, I. p. 254) attribute these currents in 
Sertularia and Campanularia to a peristaltic 
movement of the canals of the body ; which, how- 
ever, Van Beneden (Mém. sur les Campan. loc. 
cit. p. 18) has been unable to see in these Polyps. 
Erdi (Miller’s Arch. 1841, p. 426) attributes it, 
in Veretillum cynomorium, to cilia; and Will 
(Froriep’s neue Notizen, 1843, No. 599, p. 69) has 
found all the cavities of the body and corallum of 
Alcyonium palmatum lined with cilia. It is, 
moreover, certain that the currents observed by 
Erdl (Miiller’s Arch. 1841, p. 428) and Dumor- 
tier. (Mém‘"foe: cit. p. 52) in the tentacles of 
Actinia are due to ciliary action. 5 
their nutritive and digestive systems are-combined;’ 
and, as with them also, the circulating, nutritive 
liquid is chyme. See also Dana loc. cit. p. 35. 
—Eb. 
