DEVELOPMENTAL HISTORY OF THE MOLLUSCA. 41 
that we have no reason to suppose that the matter (deutoplasm of VAN Benepe) thus 
thrown into the original egg-protoplasm, together with the subsequently introduced 
male contribution of spermatozoa, is not assimilated so as to form with it an organic 
whole; rather it seems probable that the original protoplasm of the egg-corpuscle feeds 
on the matter brought to it, as does an Ameba or other unicellular organism, and that 
it is not until the final segregation of formative from food yelk on the completion of 
the blastoderm, that we can say what has not been digested, 7. e. what stands over for 
the nutrition of the new generation of blastodermic cells. 
With the development of vascularity in the peduncle and egg-capsule, longitudinal 
ridges make their appearance, and are plainly seen asa definite pattern through the 
outer egg-envelope. ‘They increase very much in complexity as the egg increases in 
size; and finally the surface of the egg presents a complete basketwork tracery, 
which is shown in an incomplete condition in the Loligo’s egg (drawn in fig. 22), and 
has been figured and described by KOLLIKER in his classical ‘ Entwickelungsgeschichte 
der Cephalopoden,’ published at Zurich in 1844. It is at this point that my observa- 
tions first come in contact with K6n.ikEr’s, who starts from this condition of the egg. 
KOLiIKer’s is the only memoir on the development of any Cephalopoda to which I 
shall have to refer in the present paper, since there has been but one short notice on 
the subject of Cephalopod embryology during the last thirty years. That notice is due 
to Prof. Metscunikorr, but is only known to me by a French abstract—like the 
Russian original, exceedingly short and devoid of illustration. I shall not have to refer 
again to METSCHNIKoFr’s paper, and there are but few points in KOLLIkER’s work which 
come into contact with mine. At the time when Prof. K6LLIKeR made his admirable 
observations, many questions were in a very different condition to that which they hold 
at present; and microscopes were not of their present efficiency. Moreover, Prof. 
KO6.LiikER has described the early stages of postseminary development from the exclu- 
sive study of the eggs of Sepia and Argonauta, and mainly studied them by means of 
surface-views obtained with a low power of amplification. 
The structure of the basketworked capsule in the ovarian egg of Sepia was figured 
and investigated by Kéuiiker. He attributes the surface-pattern to the folding of the 
vitelline membrane of the egg itself, and points out that the egg-capsule does not take 
any part init. He shows by a section of the egg, which is figured, that (what he mis- 
takes for) the vitelline membrane is thrown into folds, which are pushed inward towards 
the centre of the egg, forming in section a series of incomplete septa traversing the egg. 
These disappear, KOLLIKER shows, as the egg advances to maturity, and finally the egg 
escapes from its capsule with a perfectly smooth surface. If in the year 1842 our 
present methods of cutting and clarifying tissues for study with the microscope had 
been known, it would have been quite a simple matter for KOLLIkER to have ascer- 
tained that he was mistaken in supposing that the membrane which is thrown into 
folds is the vitelline membrane. 
The eggs of Sepia and of Loligo do not present any thing comparable to a vitelline 
MDCCCLXXV. G 
