262 EXPERIMENTS AND OBSERVATIONS 
the membrane or outline of the germinal vesicle is much wrinkled 
and contracted, but this is to a certain extent due to the action of 
reagents. It occurs in preparations made with corrosive sublimate 
and acetic, and with picro-sulphuric acid, but in some preparations 
made with chrom-osmic acid it is less marked. On the other hand, 
in a piece of the ovary from a flat fish just killed and placed on a 
slide beneath the microscope, without the addition of water or any 
reagent, the wrinkling of the membrane of the germinal vesicle is 
very frequently observed in the larger transparent ova and in those 
in which yolk is commencing to develop. It is probable enough, 
therefore, that this wrinkling of the membrane is, to some extent, a 
natural phenomenon occurring during life, although there can be no 
doubt that in many preparations the nucleus has been further altered 
and contracted by the action of the reagents. 
This wrinkling of the membrane is the same condition which is 
described by Scharff * as the formation of peculiar protuberances all 
over the outer surface of the germinal vesicle in eggs of the gurnard. 
His fig. 9 agrees closely with the appearance presented in many 
of my own preparations. But he gives an extraordinary inter- 
pretation of the changes taking place, which I am quite unable to 
accept. 
He states that the protuberances containing nucleoli are separated 
off, carried towards the exterior of the egg, and there form the yolk 
spherules, having the appearance of cells containing a nucleus. I 
am unable to trace any direct connection between nucleoli and yolk 
spherules. I have failed to find after long and careful scrutiny 
the shghtest evidence that the nucleoli migrate at all. It is true 
that occasionally a nucleolus in a prepared section appears to be 
outside the nuclear membrane, but I find this is always due to one 
or other of two causes ; either the nucleolus has been bodily pushed 
out of its place by the edge of the razor which failed to cut through 
it immediately, or the pouch of the wrinkled membrane has been 
cut in such a manner in the section that it is separate from the 
interior of the main germinal vesicle. In the latter case the 
connection can be seen in the next section. In the former case the 
artificial nature of the occurrence is easily proved by observing 
that the direction in which the nucleolus has moved is the same as 
that of other striz in the section caused by the razor. The nucleoli 
become very hard after the action of chromic acid, and it is in 
preparations from tissue hardened with this reagent that such dis- 
locations usually occur. The hypothesis that the nucleoli give rise 
to the yolk spherules is untenable from the nature of the case, for 
the spherules are very numerous, and as the egg ripens form a bulk 
* Quarterly Journal Micr. Sci., vol. xxvili. 
y 3 
