43 2 
MONTGOMERY. 
[Vol. XV. 
the size of the nucleus, seldom small. It is the rule that in 
one, sometimes in all the nucleoli, a large unstaining globule 
is present, which has the appearance of a vacuole (Figs. 284- 
287, 298); no nucleolus has more than one such globule. Quite 
often there is only a single large vacuole-containing nucleolus 
in a nucleus ; or there may be from one to six nucleoli, only 
one of which contains a vacuole, and then the latter is usually 
the largest ; or again, there may be two or three large nucleoli, 
nearly equal in point of size, each of which contains a vacuole 
(of course numerous intermediate stages may be found). There 
is certainly a successive production of nucleoli, but it is diffi¬ 
cult to decide whether some of these after leaving the periphery 
of the nucleus fuse together, or whether some divide into smaller 
nucleoli. Now it seems probable that those nucleoli which are 
formed first are usually unequal in size, both in the same nucleus 
and in different nuclei, as a comparison of the figures shows. 
And though a gradual fusion of the nucleoli might play some 
part in the youngest germinal vesicles, nevertheless it would 
seem more probable that we have to do in these early stages 
with divisions of the nucleoli, especia^y since in the following 
stage they are much more numerous, as well as smaller. Fig. 
287, in which three apposed nucleoli are to be seen, may thus 
represent a division of a single nucleolus. It is not unlikely 
that the unstaining globule within a nucleolus might aid, if it 
is not the direct mechanical cause of, such division. This first 
nucleolar stage is then characterized by the successive forma¬ 
tion of a few comparatively large nucleoli at the periphery of 
the nucleus, and the migration of these towards the center ; 
the presence of large vacuoles within some of the nucleoli is 
also a criterion of this period. 
Second nucleolar stage .—We find a group of numerous 
nucleoli near the center of the nucleus, which are frequently 
more numerous than in our Fig. 292. At this stage they 
attain their smallest dimensions, and are approximately equal 
in size ; they are completely homogeneous and contain no 
vacuoles. The total number of the nucleoli is apparently 
greater at this stage than at any other. 
Third nucleolar stage. — This is characterized by an increase 
