BZ MR. F. E. BEDDARD ON THE DEVELOPMENT AND [Dec. 7, 
contact with the interior mass of cells, the follicular layer being at 
such points indistinguishable. 
It is possible that the difference of size in the nuclei corresponds 
to a distinction between “ primitive ova” and “ germinal cells”? such 
as has been described by Semper, Balfour, and so many writers in 
other Vertebrata ; in this case the larger nuclei will be the primitive 
ova. This suggestion must be of course only regarded as such; I 
have no real evidence to offer except the different size of the nuclei. 
In very many instances a degeneration of the nuclei could be 
observed. This takes place in several ways, some of which may be 
stages in the same series. Some of the nuclei (figs. 14,17) remain 
of the same size and shape as the normal nuclei, but show a much 
paler colour and fewer nucleoli ; in one instance (fig. 15) I observed a 
commencing disintegration of the nucleus, the substance of which 
appeared to be in a condition of solution at one point where it passed 
gradually into the substance of the cell, the limiting membrane of 
the nucleus being here invisible. In other cases (figs. 19, 20) the 
nuclei are as darkly stained as the normal nuclei or even rather more 
so, but instead of presenting a uniform oval contour, the nucleus was 
variously contorted and irregular in shape. 
The centre of the mass, however, is not entirely occupied by cells 
like those that have just been described. There is a certain amount 
of an amorphous substance (fig. 1, p), well stained with the borax 
carmine, which lies in patches between some of the central cells, and 
particularly on the outside, in the space which separates them from 
the follicular layer. This substance is of an homogeneous appear- 
ance, though lighter in colour in some regions than in others ; it is 
rather more abundantly developed in the stage next to be described 
than in the present (cf. fig. 9, Plate LIII.). This substance encloses 
patches of cells, or sometimes single cells; occasionally the proto- 
plasm of the cells has undergone a certain change at the periphery, 
where it gradually passes into the homogeneous mass surrounding 
it ; frequently scattered nuclei are to be found imbedded in it, and a 
comparison of these nuclei with those of the central cells shows 
them to be identical. The general appearance of the homogeneous 
substance suggests a coagulated fluid, and it is very like the liquor 
folliculi of the Mammalian ovum coagulated by alcohol; but this 
substance cannot be excreted by the central cells or by the follicular 
cells, because it contains numerous traces of them in the shape of 
free nuclei with or without a certain amount of partially altered 
protoplasm attached. These facts rather indicate that the sub- 
stance in question is produced by the alteration and fusion into a 
semifluid mass of some of the central cells. This mode of formation 
is, however, not opposed to a comparison with the Mammalian 
liquor folliculi, which has been asserted by some to have a similar 
origin ; the great difference is that this semifluid substance has the 
power of forming yolk, as will be seen after the description of the 
later stages. 
There are other bodies which seem to be referable to the stage just 
described, though differing in certain structural particulars as well as 
in their smaller size. 
