$$ 256, 257. THE CEPHALOPODA. 293 
Loligina. Their walls are composed of a dense web of cells, which, with 
the Octopoda, contain round, violet nuclei, of a crystalline texture and 
resembling entirely those found in the renal cells of the Gasteropoda.” 
IT. Organs of Special Secretions. 
§ 256. 
The Ink-sac is an organ generally common with the Cephalopoda. It 
is usually pyriform, situated upon the median line of the abdomen, and 
often enveloped with a peritoneal layer of silvery lustre. Its apex points 
‘forwards and upwards, towards the funnel. The walls of its generally small 
cavity are cavernous,” and secrete the well-known black pigment, which, 
through contractions, ‘passes into the funnel, and is then expelled, mixed 
with the water of the sea, which is passing outof the body. The excretory 
duct of this sac runs along the rectum, and terminates just behind the anus, 
or opens into the rectum.” 
As an organ, also, of special secretion, ought to be regarded the com- 
pletely-closed chambers found in the shell of the Nautilina; for it is said 
that their walls, like those of the natatory bladder of fishes, secrete a gas. 
CHAPTER X. 
ORGANS OF GENERATION. 
§ 257. 
The Genital organs of the Cephalopoda are always distributed upon two 
individuals, and present very remarkable peculiarities. 
uated at the inferior or lateral portion, separates 
these bodies into two unequal divisions ; see Brandt, 
loc. cit. Taf. XXXII. fig. 22, q. r.; The Catal. of 
the Physiol. Ser. II. Pl. XXII. f. x. (Sepia) ; Delle 
Chiaje, loc. cit. Tav. XCI. XC. XCV. XCVI. 
(21, 28, 25, 26), (Loligo and Sepiola). 
9 Erdl (Carus, Erlauterungstaf. Hft. VI. p. 7) 
has published an observation on the glandular na- 
ture of these bodies, and the resemblance of their 
parenchyma with that of the kidneys of Hediz, all 
of which I have been able to fully confirm. Nev- 
ertheless, these organs demand further chemical 
and histological investigation. 
1 This organ, which is entirely wanting with 
Nautilus, and Hectocotylus, has an elongated 
form with the long-bodied species, and is large 
with those whose body is short ; see Wagner, Icon. 
soot. Tab. XXIX. fig. 20,h. i. (Octopus); Feérus- 
sac, loc. cit. Argonauta, Pl. I.» fig. 2,3; Brandt, 
loc. cit. Tab. XXXII. fig. 1, 24,0. (Sepia). That of 
Sepiola is quite remarkable in having an extraor- 
dinary development in certain individuals, at par- 
ticular seasons, without reference to the sexes. 
There are then found tio long bodies adherent by a 
constriction to the sides of the otherwise simple ink- 
sac. These lateral bodies are black, composed of a 
glandular tissue continuous with that of the sac, 
25* 
and surrounded by a muscular layer. Peters 
(Miiller’s Arch. 1842, p. 329, Taf. XVI. fig. 1, b. 
b. 8-10) has seen it contract regularly. With the 
specimens preserved in alcohol the ventral surface 
appears colorless. Grant appears to have been un- 
aware of this increased development at certain 
times with Sepiola, for he has attributed to them 
in general a trilobed ink-sac (Transact. of the Zool. 
Soc. I. p. 82). In the Sepiola figured by Delle 
Chiaje (Descriz. Taf. XI. fig. 4, 1.), the two lateral 
lobes in question are very distinct. 
2 Delle Chiaje, Descriz. I. p. 74, Tav. XII. fig. 
1,2. Tav. XVIL. fig. 4 (Loligo, Octopus and 
Eledone). 
3 This last case obtains with the Loligina. 
4 Owen (On the Nautilus, p. 47, or Isis, p. 39) 
has, it is true, left undecided the question whether 
these chambers are filled with gas or with liquid ; 
but, according to Vrolik (Ann. of Nat. Hist. XI. 
p. 174) the chambers of Nautilus pompilius really 
contain a gas composed chiefly of nitrogen without 
any trace of carbonic acid. These chambers resem- 
ble, in many respects, the swimming bladders of 
fishes, and, like them, serve, perhaps, to facilitate 
the ascension and descension of these animals in 
the water. 
