30 The Significance of Sex. [ Jan. 
II.—The Significance of the Cell-Nucleus to the 
Problem of Sex. 
(a) CELL-STRUCTURE IN GENERAL. 
Microscopic examination of cells in the living state, or treated 
by the simple hardening, staining, and section-cutting methods of a 
few years ago, can give us only a superficial knowledge of cell- 
structure. With such methods the first step taken was to distin- 
guish the protoplasm as differentiated into the outer membrane 
or cell-wall, the more fluid and granular contents, and the gener- 
ally spherical and central zwcleus. The last body often carries 
a nucleolus; and nucleus and nucleolus may sometimes be in- 
, creased in number, or, again, they may apparently dissolve to be 
later reconstituted. Our next step under this technique was to 
distinguish a primary and a secondary plasma,—the former the 
protoplasm proper, the latter the dewtoplasm (paraplasm, meta- 
plasm, etc.), formed by processes of absorption, assimilation, and 
degradation of the protoplasm. The former is active, 4/e-sud- 
stance, the latter passive, food-substance. The protoplasm is more 
firm and hyaline, abundant near the wall and the nucleus, and 
forms coarse trabecule, traversing and bathed by the deutoplasm. 
The latter substance is mainly “ cell-sap,” in which float granules, 
oil-drops, yolk-spheres, etc. The difference in the size of cells is 
due mainly to difference in the amount of deutoplasm they con- 
tain. We are not surprised, therefore, to learn that the yolk of a 
hen’s egg is homologous with a microscopic cell, but we cannot 
say that it contains no more pure protoplasm than the latter. 
The third step was taken as a result of studies of the phe- 
nomena ‘of fertilization. The nucleus of the egg, the germinal 
vesicle, often shows a structure quite comparable to that of a 
“ typical” cell, and the fact that it was seen to conjugate with the 
spermatozoon certainly pointed to its autonomous nature; but at 
first the true import of this conclusion was obscured by theories 
as to the multicellular nature of the ovum. 
Our knowledge of the cell has, owing to improved technique, 
- been wonderfully advanced during the last decade by the labors 
of cytologists, led by Strasburger and Flemming ; and at present 
the work of Carnoy and of Gaule promises a new era in which the 
science of the cell shall rise to the dignity of a grand division of 
biology. We shall treat of Cytology only so far as a knowledge 
