1894,] Chemico-Physiologieal Discoveries: The Cell. 
103 
and we are led to infer marked differences in chemical compo- 
sition from the behavior of the several parts of the cell to- 
ward the many pigments or dyes used in histological investi- 
gation. There can be no manner of doubt that the differences 
in color between the nucleus and the cytoplasm of the cell, for 
example, as brought out by the agency of various pigments 
is due to differences in chemical composition. Again, as you 
are well aware, Ehrlich has been able to discriminate between 
the different varieties of granules found in cell protoplasm by 
their behavior toward neutral, acid and alkaline aniline 
dyes. Thus,in the centresome we have a mass of differentiated 
cytoplasm, which as Watasé* has shown in the egg of Unio, 
may be made to stand out with great distinctness by means of 
acid-fuchsin, while the spindle fibres and the rays of the aster 
remain practically unstained, thus clearly pointing to differ- 
ences in chemical composition which are well worthy of note. 
Again, there are still other granules frequently present in the 
cytoplasm of many cells, staining dark with osmic acid, 
which indicate still other differences in chemical composition. 
But our knowledge concerning the chemical nature of proto- 
plasin is far too imperfect and scanty to admit of our drawing 
any other than the broadest generalizations from the affinity 
the protoplasm may show for various pigments. 
Further, as you well know, the nuclear constituents have 
been divided by various investigators, as by Flemming, into 
several groups according to the action of different stains; 
thus, we have the chromatic substance or chromatin, which 
stains readily with the aniline dyes and which comprises 
especially the nuclear network, then achromatin, or that por- 
tion of the nucleus which does not stain readily, as the nuclear 
matrix and the nuclear membrane. 
Such statements as these may be added to almost indefi- 
nitely, but for our purpose the above are amply sufficient to 
indicate the existence of marked chemical differences in the 
cell cytoplasm and karyoplasm. And, indeed, that is all they 
do indicate; they give us very little knowledge of the real 
nature of the substances which are the cause of these differ- 
‘Homology of the Centresome. Journal of Morphology, Vol. 8, p. 433. 
