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MONTGOMERY. 
[Vol. XV. 
size of the other; but when three nucleoli are present, either 
(i) one is particularly large, and the other two small; or (2) two 
are large, and the third is much smaller than either ; or (3) all 
three are large, the smallest being about one-half the size of the 
largest. In the two cases of nuclei with four nucleoli apiece, in 
the one there were two larger and two smaller nucleoli, in the 
other one large and three small ones. 
The nucleoli vary from a spherical to an oval shape. In the 
smallest usually no vacuoles (; n . Vac .) are to be seen, but such 
vacuoles are always to be found in the larger nucleoli. In the 
largest there is usually a large excentric vacuole, while small 
ones may or may not be present in other portions of the nucle¬ 
olus. In nucleoli of medium size it is most usual to find a 
number of small vacuoles. These vacuoles have already been 
noticed in numerous other gregarines, but I would call especial 
attention to a remarkable polarity of the nucleolus with regard 
to their position. In all those nucleoli in which vacuoles 
occurred, with the exception of not more than five or six, the 
single large vacuole, or the group of smaller ones, was situated 
at that pole of the nucleolus nearest the nuclear membrane 
(Figs. 7-9, 16, 17-19). There are almost no exceptions to 
this phenomenon in the smaller nucleoli, those, namely, in which 
only a single small vacuole or a few small ones are present. 
Accordingly, it would seem to be the rule that the vacuoles 
first appear in that portion of the nucleolus which approaches 
nearest to the nuclear membrane. The number and size of 
these vacuoles increase with the size of the nucleolus ; or, as 
is more usually the case, as the nucleolus increases in size they 
gradually fuse together to form a single large vacuole, which 
may occupy the greater part of the nucleolus (Fig. 15). Thus 
the vacuoles first arise at one point in the nucleolus, so that 
here one can speak of a polarity of the nucleolus ; but as the 
vacuoles increase in number and commence to fuse together 
the fluid substance of them begins to diffuse more widely 
throughout the nucleolus, so that evidences of this primitive 
polarity gradually become obliterated. 
The ground substance of the nucleoli is very finely granular, 
and stains deeply red with eosin, and brownish red with the 
