DEGENERATION OF THE EGG-CELLS OF THE GASTROPODS. 
289 
the shaft-like part of the cell represents the nutritive substance which 
may be regarded as the «raw substance» of the vitelline bodies. 
In searching for the cause of degeneration, I have to refer to 
some data of the literature. About Vertebrates it has long been known 
that their eggs degenerate under normal conditions as well, which 
means that the observations were made on animals examined shortly 
after their capture, and thus their eggs could not have been .changed 
pathologically in consequence of unnatural conditions of life. According 
to Brünn (4) the eggs of the sparrow periodically atrophy which atrophy 
coincides with the breeding period and the nourishing of the young 
issue. A similar degeneration was observed by Dubuisson (6) in the 
eggs of Triton. But as regards the degeneration described above, more 
interesting are the researches referring to animals held a long time 
in capture under unnatural circumstances. Such observations were made 
by Mingazzini (IB), according to whom the degeneration of the egg- 
cells is a very common appearance in Beptiles and Amphibians held 
for a considerable time in capture and nourished insufficiently. Perez’s (16) 
observations also fed to conclusion that the degeneration of the egg- 
cells of Molge marmorata and M. palmata was the result of star¬ 
vation. The mesh-like structured eggs of Myelophilus piniperda, already 
mentioned, occur — according to Knoche — in animals which have 
starved for a considerable time. 
The examples enumerated above are — as regards our case in 
discussion — very important, since the sameness of the results 
points toward this identity of the causing factor, though some circum¬ 
stances contradict the conclusion. The animals mentioned were held 
captive for a considerable time which fact sufficiently explains the dege¬ 
neration of their ova; on the contrary the Gastropods investigated by 
the author were collected in places which were most favorable for their 
existence, and conserved immediately after their capture. In spite of 
this I am of the opinion that the degeneration of their ova is a result 
of insufficiency of nourishment. It is a very important circumstance 
that the egg-cells begin to degenerate in the time when the genital 
gland reaches the height of its function, i. e. when the growth of 
the younger generations of the germ-cells, and particularly that of 
the spermatozoa is in its fullest vigour. This increased function is 
naturally connected with a great consumption of substance, and in the 
struggle for the nourishment the smaller, more mobile and vigorous 
male germ-cells are in great advantage in comparison with the less 
agile larger female germ-cells, and take the food from them. The egg- 
cells weakened in consequence of insufficiency of nourishment can- 
19 
Annales Musei Nation alis Hunt tarici IX. 
