1887} = The Significance of Sex. 231 
structure, Possibly it does not get thoroughly mixed with the 
nuclear idioplasm in a molecular or rather gemmular intimacy, 
but as this process of segmentation and fusion is repeated for 
each division, there is no reason to suppose that after a while this 
may not be attained. Thus it is that every cell-division is a ferti- 
lization. 
In the conjugation of Stylonychia, there is a fusion of nuclei 
with nuclei across the body, first uniting the nuclei of the two 
gametes; and then the anterior nucleus (zygote) fuses with the 
posterior one, after which the two nuclei are reconstituted. Possi- 
bly, Engelmann says, the nucleoli (endoplastules) do likewise. 
In copulation of Stylonychia there is segmentation of the nuclei 
and probably of the nucleoli, but Engelmann was unable to 
observe any transfer of material between the gametes. The nu- 
clear fragments fuse to one body and bud off the nucleoli, but 
here there is disagreement, for in another case it seemed as if 
the nuclear products were extruded (Bütschli), the nucleoli be- 
came four in number, one disappeared, two became the new 
nucleoli, and the fourth, dividing, formed the endoplasts. 
In copulation of Anoplophrya, Schneider could not observe 
` any exchange of nucleoli, but the nuclei sent processes into the 
apposed cell, which became budded off mutually and fused with 
the remnant of the original nucleus to form a new nucleus, 
while the nucleolus came from one of the four segments into 
which the nucleolus divided; the other three disappeared. In 
Paramecium, the endoplastule and the endoplast get segmented, 
the former usually into four, the latter into many, granules. 
Then there is a fusion of the fragments, but-as to how this is 
done, and as to whether there is any mutual interchange of idio- 
plasm, is a question which has received a dozen different answers, 
Greeff thought the nucleolus was a semen capsule and the nu- 
cleus an ovary. The “eggs” that came from the “ ovary” being 
fertilized, developed to living embryos viviparously. Stein called 
that part of the nucleus which remained after budding off eggs 
the “ placenta,” Balbiani, that the eggs were laid, and Engelmann 
also, with many other early observers, held views of a similar 
nature, according to which we had here a true hermaphodite, 
Engelmann subsequently modified his views to some extent, but 
Bütschli attempted to bring the phenomena into line with his 
observations on tissue-cells, and so he held that the nucleus is — 
