$ 229. 
THE CEPHALOPHORA. 
267 
of the entire surface of the vitellus, but surrounds the last in a ring-like 
manner, and is gradually detached by its cephalic and caudal extremities. 
pacious portion are found both male, (testes), and fe- 
male (ovarium) organs in the shape of sacs, which 
are not attached in any way tothe main molluskig- 
erous sac. These genital organs bear no resem- 
blance whatever to ordinary testes or ovaria, except 
in their products, which are identical. When the 
ovarium is perfectly developed, it and its capsule 
burst and discharge the ova which are then con- 
tained in the main molluskigerous sac; after this, 
fifteen to twenty ova become invested with a com- 
mon capsule, though their fecundation takes place 
previous to this investment. Upon this succeeds 
their development. 
The sperm-capsules vary from four to eighteen in 
number, and lie perfectly free in the main sac, not 
far from the ovary. ‘The spermatic particles are 
set free by the bursting of these capsules, and they 
resemble those of the Gusteropod Mollusks in shape 
and form. 
The development in the egg here proceeds exact~ 
ly as with the Mollusca (e. g. Actaeon, according to 
Vogt), and finally it assumes pretty definite char- 
acters indicating rather its relation to the Pectini- 
branchia. Of its zodlogical character as a Mol- 
Jusk there can, therefore, be no doubt, and the whole 
story in a word is, that a true Mollusk is developed 
within a Synapta, not by g » but by 
means of the normal sexual products which occur 
under otherwise amorphous and anomalous parts 
and conditions. 
that the tion of this a} ous sac is 
not special or direct with the Synapta, but this last 
appears to serve asa kind of nest in which the 
Mollusk carries out its ulterior and remarkable 
changes. i 
Such being the facts, the question now arises, 
What interpretation shall be given these phenome- 
na? The distinct sexual mode of reproduction 
would seem to remove these phenomena from the 
category of the so-called alternation of Generation, 
or gemmiparity as we now understand it. Then 
again, the doctrine of ‘‘ heterogeneous generation ” 
as suggested by Muller, does not seem to me ad- 
missible, beside being particularly unsound, — for 
if an animal can produce, by true sexual generation, 
an offspring zodlogically dissimilar to itself, zodlo- 
gists may well look about for the stability of their 
science. If I may be allowed an opinion or rather 
a@ view on a subject on which I have made no ob- 
servations, I would say that an approximate solu- 
tion of this seems obtained by admitting the 
It should, moreover, be remarked ° 
Why may not this Mollusk undergo a form of 
retrograde metamorphosis during which its life ig 
parasitic and very peculiarly connected with the life 
of another and wholly different animal? Or again, 
why may not the phenomena observed be the final 
conditions of certain low modes of life which are 
connected with points in the economy of these 
animals that we do not yet understand? I throw 
out these remarks in a suggestive way. If we re- 
fer for a moment to the historical relations of the 
Cestodes, it will be perceived that there was a time 
when the conditions of their life were equally if not 
more obscure. Siebold, however, has shown that 
here, although the path taken by Nature is circuit- 
ous and intricate, yet, after all, no new features of 
a heterogeneous nature are introduced. and that 
all required for the observer was care and pa- 
tience. It does not seem to me any more im- 
probable that this Mollusk should have entered im 
some of its stages the body of the Synapta, since 
the anomalous undeveloped forms of many Iel- 
minthes pursue a similar course. Let the natural- 
ist also bear in mind the remarkable phenomena of 
the Hectocotyli. In the Nachtrag to this first ac- 
count before the Berlin Academy, but more espec- 
jally ina subsequent and more complete account 
. (Ueber die Erzeugung von Schnecken in Holothu- 
rien, in Miller’s Arch. 1852, p. 1) lately given, 
Miller discusses still further these facts. After 
some remarks upon the importance of a careful 
study of the embryology of this curious form, he 
says: “TI do not give up the hope that we may yet 
determine at least the genus of this Mollusk ; and I 
found this hope mainly upon the very characteris 
tic form of the spermatic particles, beside the other 
features above mentioned........ The sperm- 
atic particles of Natica and its allies are yet un~ 
known. .... . In studies bearing upon this mat~ 
ter, one should particularly bear in mind the ter- 
minal enlargement of the spermatic particles, which 
up to this time has been observed in no Gasteropod, 
but which with the spermatic particles of the Mol- 
lusk in question is never wanting.” Although for 
some time familiar with the details of the spermatic 
particles of the Gasteropod Mollusks, yet I have . 
very recently reéxamined the spermatic particles 
of Natica (NV. heros) with reference to this point. 
They resemble closely those of the pulmonary Gas- 
teropoda (Heliz, for instance), and consist of a well- 
defined cork screw head to which is attached a 
very deli tail; they agree, therefore. in general 
possibility of new and hitherto unknown parasitic 
conditions in the life of the Mollusk in question. 
with the form given by Milder of the Mollusk in 
question. — Ep. 
