800 THE CEPHALOPODA. $ 261. 
mouth, and producing a communication between the internal and external 
sacs. 
The vitellus of the internal sac gradually disappears, and is replaced 
through this canal of communication by that of the external sac. During 
the successive development of the organs contained in the cavity of the 
mantle, the internal vitelline sac is divided into lobes which are finally broken 
up and absorbed; while the intestinal canal, the remaining organ of the 
embryo, is developed, quite independently, from the vitelline mass. 
As to the development of the males (Hectocotyli) of Argonauta and 
Tremoctopus, nothing is yet known except of its last period. It has been 
observed, however, that, during the time they are in the egg, they have their 
proper form which is so remarkably different from that of the females, 
6 Had the fact that the Hectocotyli exist in the 
egg with their proper form, among the eggs of fe- 
males of certain species, been properly observed, 
the true relations of these supposed parasites to the 
animals in which they live, wold have been known 
long ago. A passage of Maravigno, first properly 
interpreted by Kélliker (Ann. of Nat. Hist. loc. cit. 
p. 414) shows clearly that this Italian naturalist, in 
his researches connected with Argonauta, was in 
error only as to the eggs which contained the male 
individuals. 
* [§ 261, note 6.] The subject of the Hectocoty- 
jus to which such frequent mention has been made 
in these pages, is one that has elicited a good deal 
of attention of late years, but, now, happily, seems 
pretty definitely settled. Chief among these inves- 
‘tigators are H. Miller, and Vérany and Vogt. 
They have pretty clearly shown the non-independ- 
ent character of these forms. The details of these 
researches cannot here be given; it may be re- 
marked, however, that these observers have all 
studied these forms upon living specimens on the 
coasi. .It has been shown that the Argonautae on 
which these Hectocotyli are found, have a highly- 
developed testicle, the situation and structure of 
which correspond to those of the common Cephalo- 
poda, and which communicates with the Hectoco- 
tylus. 
In conclusion, I may quote H. Miiller’s own 
words: “Itis then proved that the Hectocotylus 
is formed on amale Argonauta, and is nothing but 
an arm metamorphosed in a very irregular man- 
ner. This arm, or the Hectocotylus, is detached 
He says thus: ‘ Mais encore que le petit poulpe, 
au sortir de l’oeuf, ne ressemble pas entiérement a 
ce qu’il sera par la suite; c’est alors une sorte de 
petit ver (vermicello) pourvu de deux rangées de 
ventouses dans la longueur, avec un appendice fili- 
forme a une extrémité, et un petit renflement vers 
Pautre, od il parait que sont les organes de la di- 
gestion.””»— (Ann. d. Sc. Nat. VII. 1837, p. 173.) 
The mode of development of these males differs 
undoubtedly very much from that of the females.* 
when it has been filled with the sperm which is 
formed in a true testicle of the Argonauta itself, and 
it then plays an apparently independent life. In this 
condition. it meets the female Argonautae which, 
by a true copulation, it impregnates, as I have 
observed with the Hectocotylus of a Tremoctopus, 
and it resembles in this, as also by its movements, 
by a kind of circulation, and by the long duration 
of its life after detachment, a true male animal.” 
For the literature of this subject, see, beside the 
writings referred to in the above pages, Kélliker, 
Transact. Linn. Soc. London, XX. 1846, p. 9, Pl. 
I. ; Bericht von der zootomischen Anstalt zu Wiirtz- 
burg, Leipzig, 1849, p. 67, Taf. I. IL; Power 
(Madame) Mollusques Mediterranéens, lre partie 
Genes, 1847-51, p. 34, 126, Pl. XLI. ; Vérany and 
Vogt, Aun. da. Sc. Nat. XVII. 1852, p. 146, Pl. VI. 
-IX.; H. Miller, Ann. d. Sc. Nat. 1852, XVI. p. 
182; also, in extenso,; in Siebold and Kaélliker’s 
Zeitsch, IV. p. 1, Taf. I. and p. 346; and Siebold, 
in Ibid. IV. p. 122. — Ep. : 
