1900] STRUCTURE AND REPRODUCTION OF COMPSOPOGON 263 
but although these cells were kept under observation for several 
hours during the afternoon and evening of the day on which 
they were collected no separation of spores was noticed. On the 
following morning, however, the dark cells were found to have 
disappeared, while the filaments presented the normal appearance. 
Although no empty cells were visible from which spores might 
have escaped, it was evident that something of this nature had 
occurred during the night. A second attempt was therefore 
made on the following evening; but nothing having transpired, 
a filament, in which many hundreds of these dark cells were 
present, was placed in a Van Tieghem cell shortly after nine 
o'clock and left till morning, when it was found to have resumed 
its normal appearance as before. In place of the dark cells, 
however, which had disappeared, a corresponding number of 
spherical green free cells were found lying motionless in the 
water at a short and rather constant distance from the filament, 
having evidently escaped during the night. Observations were 
therefore resumed at a later hour on the following evening, and 
at about eleven o’clock I was rewarded by seeing the first 
aplanospore make its escape. The same type of reproduction 
was repeatedly observed on subsequent occasions, and may be 
summarized as follows: 
Formation of macroaplanospores.— Any of the superficial 
corticating cells, even in the oldest portions of the plant, or any 
of the cells of the younger filaments, even before the divisions 
preceding cortication have taken place, may become separated 
during the night into two daughter cells, in one of which the 
contents is more dense than in the other, and the nucleus larger 
and more conspicuous. As the day advances the oval chloro- 
plasts by repeated division eventually fill it almost completely, 
and it begins to assume a sub-triangular outline; one of the 
rounded angles projecting in the form of a papilla, the wall of 
which is more or less distinctly thickened, the contents just 
beneath it becoming nearly or quite free from chloroplasts 
fig. 1). As this cell or monosporangium matures, the basal 
septum by which it was originally separated from the other 
