68 
Wager and Penis ton. — Cytological Observations on 
that they are not sufficient to establish the identity of two kinds of 
granules, and, furthermore, that the stains used by himself, namely, methy¬ 
lene blue and haemalum, indicate clearly that there is only one kind of 
granule present. 
As most of Guilliermond’s conclusions appear to have been based on 
preparations stained with methylene blue and haemalum, it might be well 
to emphasize the fact that methylene blue is not a good nuclear stain, and 
one would not expect to find the chromatin granules differentiated by it. 
Guilliermond himself points out that the nucleolus is only faintly stained 
and barely differentiated from the cytoplasm. Haemalum, on the other 
hand, stains everything in the cell, the chromatin network, nucleolus, and 
1 metachromatin ’ granules. The differentiation in this stain is not as clear 
as in preparations stained with Heidenhain’s haematoxylin, but in good 
preparations the * metachromatin ’ granules stain black and the chromatin 
reddish blue, so that it is difficult to understand how Guilliermond failed to 
recognize the two kinds of granules. 
It is possible that Guilliermond’s inability to recognize the presence 
of the chromatin network was partly due to a fixing agent extensively 
used (picric acid), which accentuates the granular contents of the cell but 
does not sharply differentiate the threads of the network or the nucleolus 
from the cytoplasm. 
The ‘ metachromatin 5 (volutin) granules differ from the chromatin 
granules in the following respects :—(i) They are visible in the living cell 
as bright refractive granules, whereas the chromatin granules and nucleolus 
are invisible. (2) They stain deep red or black with methylene blue. The 
chromatin granules and nucleolus stain a pale blue like the cytoplasm, and 
the former are commonly invisible. (3) They remain unstained by Heiden¬ 
hain’s haematoxylin, when the chromatin granules and nucleolus are 
strongly differentiated by it. (4) They are characteristically different in 
shape from the chromatin granules, being peculiarly angular, and they may 
attain a size incompatible with the description given of chromatin granules. 
(5) They lie individually free in the cytoplasm, whereas the chromatin 
granules are arranged on a network or in close contact with the nucleolus. 
(6) They sometimes exhibit Brownian movements in the living cell. 
(7) Finally, with the exception of the one or two granules clearly visible in 
the vacuole, they are always situated outside the nuclear vacuole. 
Both the ‘ metachromatin ’ and chromatin granules are stained with 
methyl green and fuchsin, methylene blue and fuchsin, and safranin and 
gentian violet after fixing in iodine. Although at times these staining 
methods give a beautiful differentiation of both sets of granules, they 
cannot be relied upon, owing to the varying reaction of the chromatin 
network. Aniline gentian violet stains both sets of granules but does not 
differentiate them. Gram’s aniline violet method, if carefully manipulated, 
