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MONTGOMERY. 
[Vol. XV. 
a number of constrictions, or buds of nucleolar substance may 
project from its surface ; it may first break into two larger 
pieces, and then these may fragment further, or it may at once 
break into a number of pieces which are irregular in their 
dimensions (Figs. 185-188, 190, 191, 193). These fragments 
gradually wander apart from one another, the nucleus now 
being larger and already somewhat irregular in shape ; and at 
the same time each of the primitive nucleolar fragments divides 
into smaller pieces of unequal size, until when the nucleus has 
attained its greatest dimensions and most pronounced degree 
of ramification it contains a very large number of irregular 
nucleoli, which are unequal in their dimensions (Figs. 194- 
196). The figures given of this last stage show only sections 
of nuclei, and since as many as five or six sections may be made 
of one of these colossal nuclei (my sections were between 3 and 
5 /a in thickness), not one of these figures shows more than a por¬ 
tion of the total number of nucleoli in these largest nuclei ; in 
some of the latter nuclei I compute the number of the nucleolar 
fragments to be at least three hundred. But the total mass of 
nucleolar substance in these largest nuclei is certainly consid¬ 
erably greater than the mass of the primitive nucleolus at 
the time of its greatest size ; accordingly, though the division 
products of the primitive nucleolus might constitute the greater 
part of the nucleolar substance in the largest nuclei, they do 
not constitute all of it. Therefore there must be a formation 
of new nucleolar substance after the primitive nucleolus has 
divided, i.e ., a production of nucleolar substance not derived 
from the primitive nucleolus; I cannot determine the manner 
of formation of this new nucleolar substance, but would suggest 
that either new nucleoli are formed, or that the fragments of the 
primitive nucleolus increase in size by the addition of new nucle¬ 
olar substance to them. The greater number of nucleoli in the 
largest nuclei are collected in or near the thicker portion of the 
nucleus and few or none lie in the branched processes ; they are 
at this time seldom in contact with the nuclear membrane. Only 
a few of them contain vacuoles, and those which do may be re¬ 
garded as derivatives of the primitive nucleolus, the vacuoles of 
the latter still being preserved in its daughter-nucleoli. 
