184 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
the growing odcyte when the chromatin has lost its distinctly spireme- 
like form and is becoming rearranged into a more delicate granular 
reticulum. In this stage the nucleolus maintains the affinity for dyes 
that it first had, while the nuclear reticulum behaves as follows: with 
hematoxylin-eosin the original bluish color becomes purple or reddish; 
with picro-hematoxylin somewhat less blue, though never yellow; 
with acid fuchsin-methyl green mixtures the reticulum, at first de- 
cidedly green, becomes bluish or even red. At about the end of the 
growth period, when the nuclear reticulum presents the appearance 
of finely divided and uniformly scattered granules, the entire nucleus 
may stain very uniformly. Apparently at this time there is either only 
a slight chemical difference between the linin and chromatin constitu- 
ents, at least so far as our stains give evidence, or else the physical 
condition of the nuclear ingredients is the cause of the uniformity of 
staining. 
The changes which the nucleolus undergoes are either a gradual 
decrease in size, or a fragmentation, or both. ‘The time at which 
these changes begin, relative to the size of the growing egg, varies 
considerably; sometimes they start almost as soon as the egg begins 
its growth, at other times only at a later period, after considerable 
growth. Figure 39 shows the nucleus of an odcyte which has grown 
to three or four times its original diameter; the nuclear reticulum 
stains rather faintly; the nucleolus has already decreased in size and 
is composed of two pieces; in picro-hematoxylin the larger stains 
yellowish, the smaller bluish, about like the reticulum. Figure 40b 
possibly represents a later stage or, perhaps, a slightly different method 
of the breaking up of the nucleolus. Instead of the detachment of 
one large mass, there has been a separation of several smaller ones. 
This oécyte is of about the same size as the one belonging to the nucleus 
shown in Figure 39, and the staining reactions are the same. ‘The 
decrease in the size of the nucleolus becomes evident by a comparison 
with the nucleolus of an adjacent odcyte nucleus shown in Figure 40a. 
There are evidences that the nucleolus loses this substance in a liquid 
form, since the main mass remains of regular shape and sharp outline, 
while the detached parts suggest, by their form and position, that they 
are flowing along the network of the nucleus. A larger odcyte is 
represented by its nucleus in Figure 41, where, besides a single nucleo- 
lus with a vacuole, there are several smaller bodies of nucleolar origin 
distributed in the reticulum. The nucleus in Figure 42, from an 
odcyte grown to one-quarter of its final size, has several similarly 
staining nucleolar bodies in close contact with one another. Figure 
