° 
66 THE ACALEPHAE. $ 62. 
The Acalephz have no true digestive tube. But, as such, has been 
regarded a system of vascular canals filled with water, and which, de- 
parting from the stomach, traverse the whole body. But these, although 
sometimes seen to contain faeces, seem to belong more properly to the 
respiratory system. 
In nene of the Acalephae has there been found anything like an hepatic 
organ, 0 
CHAPTER VI. 
CIRCULATORY SYSTEM. 
§ 62. | 
Until lately, the longitudinal and circular’ canals which;-in some Acale- 
phae, are spread out through the entire body; have been. regarded as 
belonging to a vascular, sanguineous system. 
But more recently these 
have properly been considered as aquatic-respiratory organs; there having 
been found, moreover, other vessels of exceedingly. thin walls, and of a 
sanguineous nature. 
These last constantly accompany and surround in a tubular manner the 
aquiferous canals; and it is quite rare that small branches-are distributed 
to the general parenchyma. 
The delicate walls of these vessels have neither longitudinal nor circular 
fibres, neither. are they lined with ciliated epithelium. They circulate a 
required to thoroughly settle this point. See below, 
the respiratory organs. See also Hollard, who 
unhesitatingly regards the canals, which, with Ve- 
Zella, communicate externally by a central opening, 
as a digestive cavity, and thinks he has observed 
in their walls brownish spots representing the 
hepatic cells; see Ann. d. Sc. Nat. III. 1845, 
p. 249, PL. IV. bis. | 
9 The aquiferous canals of the respiratory sys- 
tem having been regarded as intestinal tubes, their 
orifices, which in the Ctenophora are situated at 
the extremity of the body, and in the Discophora 
upon the borders, have been considered as anal 
openings; and especially so, since in these two 
orders, accidental feces in these canals are expelled 
through these, orifices. See Will, loc. cit. p. 28, 
* [§ 61, note 9.]. Upon the-nutritive system of 
the Acalephae, see Forbes (loc. cit. p. 4), but 
especially Agass?z' (loc. cit.), who has studied the 
subject with conscientious care. There is no dis- 
tinction between the alimentary canal proper and 
the vascular system, for the one opens by large 
tubes into the other. The Acalephs, therefore, cir- 
culate chyme, and here we have the rudest form 
of circulation. If this idea is once well considered, 
the relations of their nutritive apparatus in general 
will be quickly appreciated. ~ 
The variations in the shape and form of the di- 
gestive apparatus are wide and numerous, but 
- 189, Taf. I. IV. fig. 2, 2.4 : 
and Ehrenberg, Abhandl. d. Berl. Akad. 1835, p. 
10 Acalephz possess an extraordin: digestive 
power, which is te more sitigular ds ge fie 
organ has been found on the sides of their stomach. 
Mertens (Mem. d. Acad. de St. Petersburg, loc. 
cit. p. 490, Taf. I. fig. 5, 6, a.; and p. 618, Taf. 
VIII. fig. 4, Taf. IX. fig. 1, f.), however, affirms to 
have seen in Cestum and Cydippe four vessels in 
this situation, which are perhaps hepatic organs. 
The orange-colored cords found upon the sides of 
the stomach of Stéphanomia, and which Mitne 
Edwards (Ann. d. Sc. Nat. XVI. p. 222, Pl. VIL. 
IX. X.) has taken for genital organs — may they 
not also be hepatic organs ? ¢ wh : 
, , 
their importance is rather in Zoology. See Agas- 
siz for the details of Sarsia, Hippocrene, Tiarop 
sis, Staurophora, Pleurobranchia, Bolina.~ 
Ep. , Vo : 
t (§ 61, note 10.] Kalliker (Siebold and Kélli- 
ker’s Zeitsch. IV. Hft. 3, 4, p. 313) has observed with 
Velella and Porpita a glandular mass, correspond- 
ing most probably to a liver. It had before been 
regarded as such by Delle Chidje, but Kalliker 
has given it a special description. It consists of a 
brown mass which communicates with the bottom 
of the stomachal cavity by branched, anastomosing 
ducts." ov. 
