G8 
MINUTE PARASITIC ALGiE. 
being a little eccentric, but nearer the base than the neck of the 
cell. Once within, the cell begins to expand laterally, increasing 
also in depth. Having reached nearly to an adult size, the proto- 
l)hism commences to develop green chromules. These generally 
arise as minute points along the inner surface of the cell-wall, 
from whence they radiate to the nucleus, giving at this period the 
appearance as if a number of necklaces were hung in loops from 
the sides of the cell to the nucleus. Shortly afterwards the green 
chromules appear evenly distributed through the protoplasmic mass, 
leaving, however, the neck portion colourless, and often not being 
found in the portion of the protoplasm immediately in contact with 
the cell-wall. This colourless portion would seem to lay down 
several fresh layers upon the first-formed cell-wall, giving the cell 
often quite a laminated appearance. After a few days the coloured 
portion of the protoplasm will be found to very slightly contract ; 
this gradually increases, the outer margin presenting often a 
regular undulated appearance, as it is drawn away from the cell- 
wall. In the space of a few hours this mass becomes segmented 
into a well-marked series of oval or nearly circular spores, in each 
of which at this stage a nucleus is apparent. The number of 
spores varies immensely ; as few as ten, and as many as thirty and 
more have been counted. AVhile within the mother cell the spores 
have a green hue, not at all as bright as the cell contents were 
before cell division had taken place ; but on the mother cells being 
artificially ruptured, if the zoospores have reached a certain stage 
they will be seen to escape destitute of colour ; so that I am 
inclined to think that the colouring matter may, at this stage, be 
located in the thin protoplasmic pellicle surrounding the spore 
mass. There is without any doubt in this species two series of 
these zoospores — one very much smaller in size than the other. 
The true significance of this fact I am at present unable to deter- 
mine. Cells containing the smaller zoospores, and cells containing 
the larger forms, will be found growing side by side ; but the 
number of the former far exceeds that of the latter. The motions 
of the larger spores, when set free, are slower and less vivacious 
than are those of the smaller ones. In neither one nor the other 
could I at their first exit (artificial) detect a cell-wall ; in neither, 
even with a one-eighth inch objective, could I be quite certain of 
the number or the exact position of the cilia. It would, however, 
seem as if the delicate protoplasm projected itself to one pole, and 
then became attenuated into a single cilium ; but the cell-wall soon 
makes its appearance, and this, apparently, quite independently of 
whether the zoospore imbeds itself in a host plant or not. Some- 
times these zoospores attach themselves in such masses around the 
Scliizonema frond, that there is actually no room for them to force 
their way into the mass ; often under these circumstances they will 
content themselves by simply adhering to the more or less adult 
clilorochytrium cells, and present quite the appearance of the little 
male plants of an (.Edogoiiium sitting on their large oogonium ; 
