OVIVOSITION AND THE CONSTITUTION OF THE EGG. 237 



together, large egg-bundles being thus produced, the bundles again 

 uniting to form aciniform masses {Argonauta). In Eledone also, the 

 threads from the chorion of the long eggs unite to form a stronger 

 strand, which then becomes attached to the substratum (Joubin, No. 

 21). We have ourselves found that the eggs of Eledone (apparently 

 E. moschata) are attached by their stalks to the substratum in pairs 

 or in groups of two or four. A number of such groups are found in 

 close juxtaposition, giving rise to a spawn-mass consisting of sixty 

 to seventy eggs. The long ovate eggs of this Eledone are very large, 

 measuring (including the envelope) 15 mm. in length, while those 

 described by Joubin are only about half this length. 



In Sepia, the stalks of the individual eggs become twisted together, 

 the result being a rather lai'ge strand of eggs closely arranged round 

 a central axis. These strands are attached to rocks, the female 

 covering them with her body and, by the promotion of a continuous 

 How of water, assisting in their development (Schmidtlein).* The 

 eggs of Argonauta are still further protected by the mother, as the 

 spawn is attached to the inner side of her shell and carried about by 

 her. [Nautilus (Willey, No. IV.) lays solitary eggs of great size, 

 each egg-capsule measuring 45 mm. by 16 mm. and containing one 

 egg 17 mm. long and very rich in yolk. — Er>.] 



The capsules or the gelatinous masses which surround the eggs and the 

 cementing substance by means of which they are attached are secreted by 

 special glandular portions of the oviducal wall and by the nidimental glands. 

 Where there is no such special development of glands in the genital apparatus, 

 as in the Octopoda, the eggs are surrounded by the chorion alone. This latter, 

 however, is also found round eggs surrounded by firm capsules or gelatinous 

 masses. At the animal pole of the egg, the chorion is perforated by the 

 micropyle (Fig. 105, m). 



The conditions under which copulation and the fertilisation of the egg take 

 place in the Cephalopoda are so peculiar that we must devote some attention 

 to them. In the Octopoda, fertilisation probably takes place in the oviduct. 

 The spermatophores are introduced by the help of the hectocotylised arm into 

 the mantle-cavity or the oviduct. In Argonauta, Trcm-octopus and Philonexis, 

 it is well-known that the detached hectocotylised arm of the male is found in 

 the mantle-cavity of the female. The female in the two last-mentioned forms 

 possesses a receptaculum seminis in the form of an outgrowth of the oviduct 

 which serves for the reception of the sperm (Beock). 



In the Oigopsida, as in the Octopoda, fertilisation takes place within the 

 mantle-cavity, the spermatophores being introduced into that cavity and 

 attached to various parts of its inner wall. Among the Myopsida, in the 



* Beobachtung iiber die Trachtigkeit.und Eiablage verschiedener Seethiere. 

 Mittheil. Zool. Stat. Neapel. Bd. i. 1879. 



