764 THOS. H. MONTGOMERY, JR. 
cannot be dependent upon such contact. After it has moved into 
the nuclear cavity it establishes a second connection, this time 
with a number of autosomes (figs. 58, 60 to 63), a connection that 
becomes lost when the autosomes take their places upon the 
nuclear membrane and leave the plasmosome behind them. It is 
just at this time that the plasmosome reaches its maximum size 
and shows the most irregular form. As the autosomes separate 
from it, which commences at the stage of fig. 63, the plasmosome 
becomes much paler and remains pale until it finally disappears 
by dissolution. 
Thus the plasmosome of the spermatocytes has a twofold con- 
nection with the autosomes, first during its early growth, and 
second during the time of its greatest volume. 
B. Discussion: Genesis and kinds of nucleoli 
Though Foot and Strobell (09) have denied the concomitant 
occurrence of idiochromosomes and plasmosomes in spermato- 
cytes of this species, I believe my observations of 1898, confirmed 
by the present ones, settle the matter beyond a doubt. 
The plasmosomes of all cell generations examined disintegrate 
during the prophases of mitosis, and thus are not persisting cell 
organs. In the spermatocytes they arise in close contact with the 
nuclear membrane, and at the same time in connection with the 
end of an autosome, which would suggest that the plasmosome 
is either the joint product of chromatin and cytoplasm, or 
else represents substance taken up by the nucleus from the cyto- 
plasm—this latter view being expressed by me in 1899 aftera 
study of the genesis of plasmosomes in young oocytes of Nemer- 
tini. These phenomena would indicate that the first produced 
portion of the ground substance of the plasmosome may be 
derived from the cytoplasm, and that this process may be 
directed by a particular autosome, for the plasmosome is not 
produced at any point where chromatin touches the nuclear 
membrane, thus never in the region of the chromatin plate that 
lies at the idiozome pole. However, it is to be noted that in Eus- 
chistus the plasmosome undergoes its greatest growth after it had 
