144 BULLETIN OF THE 
in situ, and have not migrated from the cnidophore through the com- 
municating canal and become incorporated into the “hepatic” cells, 
is indicated by the fact that they are found in different stages of de- 
velopment (Fig. 14, né’cy.’). One finds first of all small ovoid areas, 
which stain deeply ; later, one finds an elongated deeply staining central 
streak, while the rest of the vesicle remains colorless. This central 
streak is the proximal part of the thread. In some cases I have seen in 
the “hepatic” cells the larger kind of nematocyst mentioned by Alder 
and Hancock (55, Expl. Fam. 3, Plates 7 and 8, Fig. 16); in fact, 
they seem to occur quite as abundantly here as in the cnidophore. 
Comparing the origin of nematocysts in the Alolidee and Hydra, — for 
a knowledge of which in the latter group we are indebted among others 
to K. C. Schneider (90, pp. 332, 345), the most striking difference is 
that the nettle capsules in Hydra arise in the ectoderm only (so it is 
maintained), and that those which do occur in the entoderm have not 
been formed there, but have been devoured. In Adolis, similar capsules 
arise in diverticula of the alimentary tract, and therefore from entoderm. 
Secondly, the nettling capsules of Hydra are formed in indifferent cells 
lying at the base of the ectoderm; in Aéolis they are produced in the 
large “hepatic” cells. Finally, in Hydra only one nematocyst is formed 
in a single cell, and this comes to occupy nearly the whole of it; in 
AEolis several nematocysts (Figs. 13, 14) are produced in a single cell. 
This comparison raises the question whether the so called hepatic cc- 
cum is properly named,— whether its cells have either the function of 
storing up reserve stuff or of secreting digestive fluids. To this question 
I can give no final answer, but it is worthy of note that the “hepatic” 
cells of Aolis do contain numerous small granules which stain deeply in 
hematoxylin. This is true even for the cells which produce nematocysts 
(Figs. 14,15). A comparison with sections of the hepatic ceca of Doto 
coronata treated in the same way shows, however, that the “hepatic” 
cells of AXolis are smaller and contain smaller granules than do those 
of Doto, in which genus, of course, no nettling organs are formed. 
From their smaller size, and the smaller size of the contained granules 
(whether these are stored food stuff or katabolic product), I am inclined 
to regard the hepatic function of the cells forming the wall of the ececum 
of Aolis as less important than in Doto. 
The sum total of the nematocysts in the hepatic cecum of any ceras 
is much greater than in the ecnidophore. On physiological grounds the 
latter term is in Aolis applicable to the entire cecum, and not merely 
to its distal part. 
