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MONTGOMERY. 
[Vol. XV 
matin, and considers the nucleoli to be only isolated masses of 
chromatin surrounded by linin sheaths ; these observations 
have not been corroborated by any other writers and would seem 
to be due to faulty methods of fixation. 
In opposition to Meunier (’86), and in agreement with most 
investigators, I must conclude that vacuoles are normal struc¬ 
tures in nucleoli, since they may be seen after the most diverse 
methods of fixation, and their size and number are not only to 
some extent limited for the particular cell, but are also different 
at different periods in the metamorphoses of the nucleus. It is 
the rule that the youngest nucleoli are homogeneous, and that 
vacuoles first arise when they have increased in size. Their 
size and number vary at different phases in the development 
of the nucleolus. Very frequently a number of smaller ones 
appear, and then these subsequently fuse together and produce 
a larger one. The nucleoli of egg cells are characterized as a 
rule by more numerous or larger vacuoles than those of somatic 
cells, and in many somatic cells these vacuoles appear to be 
wholly absent. The vacuolar substance appears in some cases 
not to be a derivative of the ground substance of the nucleolus, 
but to be derived from without the nucleolus (ova of Doto and 
Montagua). Perhaps this vacuolar substance always has an 
extranuclear origin, since in many cases a germinal spot grows 
larger merely by an increase in its volume, while the ground 
substance seems neither to increase nor diminish. 
The alveolar structure of nuclei as described by Purcell (’94), 
Schaudinn (’94), Korschelt (’ 95 ), and Lauterborn (’95b) is prob¬ 
ably referable to the regular distribution of equal-sized vacuoles 
in the nucleolus. 
A “ Kernkorperchenkreis,” a shell of minute granules 
arranged concentrically around the nucleolus, has been de¬ 
scribed by Eimer (’71, ’72), Auerbach (’74a, who considered it 
to be the result of opposing repulsive forces of the nucleolus 
and nuclear membrane), Brass (’89), Pfliicke (’ 95 ), Platner (’89a), 
Smirnow (’ 90 ), Engelmann (’80), Carnoy and Lebrun (’97a). A 
more or less similar phenomenon has been described by me for 
ganglion cells of Doto. Such a nucleolar circlet must be con¬ 
sidered, in most cases at least, an artefact. But in this cate- 
