290 MR. F. E. BEDDARD ON THE | May 4, 
lopment of Bombinator’; but there are certain facts adduced by 
Gétte which require to be recorded in Lepidosiren before my opinion 
can be expressed without hesitation. G6tte observed a fusion of 
the nuclei as well as of the protoplasm of the primitive germinal cells ; 
I have not been able to detect any such fusion in Lepidosiren; 
on the other hand it is difficult to interpret my results so as to 
regard these ova as equivalent in each case to a single cell. As 
already mentioned, the series of ova between the earliest stage where 
a mass of follicular cells contained a nest of primitive germinal cells, 
and the latest stage when the ovum was surrounded by a single 
layer of follicular cells and separated from them by a delicate mem- 
brane, is fairly complete ; there seems to be no doubt that somehow 
or other the numerous primitive germinal cells of the nest result in 
the formation of one ovum. There were no signs of the separation 
of any of these cells to form a number of different ova, as Balfour 
has described in Scyllium; none of the central cells became larger 
than the rest, and the follicular epithelium, which was specialized as 
such in the earliest stage observed, showed no breaks in its continuity 
at any time; if the ovum really represents one of the primitive 
germinal cells, the rest serving as pabulum, it is remarkable to find 
that this cell shows no difference in size or structure from the rest 
as development proceeds. 
The appearance of a fusion of some of the cells, which strongly sup- 
ports my view of the case, is illustrated in Plate XXVIII. fig. 7, 7; the 
homogeneous mass depicted in that figure contains a few nuclei, and 
occasionally a certain amount of the cell-protoplasm still unaltered 
centrally, but peripherally shading off into the supposed protoplasmic 
mass. It might perhaps be supposed that this peripheral darkly- 
staining mass is really due to the coagulation of some fluid substance ; 
but in that case the appearance of nuclei, without any cell-protoplasm 
in its interior, would have to be explained, and more particularly the 
presence of yolk-particles which seem to be formed by its meta- 
morphosis. 
For the present I am unable to say any more about the develop- 
ment and maturation of these ova; the most important matter that 
requires further investigation is the mode of origin of the germinal 
vesicle; but there are obviously other points that remain to be dis- 
covered before the whole history of these ova can be cleared up. 
It might be supposed that the facts described in this section do 
away with the necessity of any immigration of follicular cells; the 
yolk has been shown to originate largely in the primitive germinal 
cells, and many of the free cells remaining in the interior of the ovum 
during later stages are no doubt derived directly from the primitive 
germinal cells. In the earlier stages the follicular cells, although 
forming a distinct layer, are not individually very different from the 
central cells of the nest; hence their proliferation and migration 
inwards is not surprising. It has been already mentioned that the 
yolk commences to be formed very early in the follicular cells as 
well as in the central cells, so that the former evidently takes a 
1 * Entwickelungsgeschichte der Unke.’ 
