108 _ BOTANICAL GAZETTE [ AUGUST 
Material in the laboratory showed the time for the escape of the 
zoospores to be usually from seven to ten o’clock in the mort- 
ing. This probably varies with the changing conditions at the 
seashore, and since the alga was submerged for only a few 
hours twice a day, it seems likely that the time of zoosport 
discharge varies with the tides. Efforts to establish this fact 
were unavailing. Observations made during the night wer 
_ likewise without result. Perfect aeration was found to be col 
ducive to the formation and discharge of large numbers of 
zoospores. 
The existence of two kinds of zoospores and the fact that 
conjugation takes place in certain closely related genera would 
naturally lead to the supposition that something of the sam 
kind occurs in Chlorocystis. De Wildeman (4) quotes Lager 
heim as having observed copulation, but I am unable 1 
find such a statement in any of Lagerheim’s papers. He does 
mention having seen two kinds of zoospores, and considers | 
probable that the larger spore is formed by conjugation, but! 
think does not claim to have seen the process. From my ide 
observations I can say that it is certain the larger zoospores ae 
not formed by conjugation, and that it is possible for both sizes 
of zoospores to develop into new plants without any fusio® 
This point was carefully investigated by means of Van Tieght® 
cell and other cultures, and the zoospores were observed durilf 
their escape and final coming to rest. There was at no time ay 
appearance of conjugation, and the development of the spores 
whether of the large or small variety, was always the same, 
cells produced being similar in every particular to the charact 
istic adult plants. It may be that under different physiologi® 
conditions conjugation might occur, but at the present time ™ 
light can be thrown upon that point. 
When a zoospore comes to rest upon the surface of the hos 
plant, its cilia disappear and a thin gelatinous wall is formé 
around it. The red spot is lost to view and the Py™ 
becomes more prominent. If the zoospore is to develop ¥* 
the host instead of merely attaching itself to the surface, *’ 
