Fisston-products of a Parasitic Alga. 177 
aggregates, some of the individual units of which may often 
be seen entire and undivided, while the contents of others are 
in different stages of fission down to the final stage of spore- 
formation. 
It seems probable that sometimes the swarm-spores are 
formed by a simultaneous segmentation of the cell-contents 
into the brood of spores, but in other cases, as was clearly 
shown by G. Klebs* for Ch. Lemna, the cells undergo 
successive processes of fission till the swarm-spores are pro-— 
duced. This latter kind of process I have found to occur 
very abundantly in Ch. Knyanum. 
Multitudes of partially empty spaces may be seen con- 
taining large or small specimens of these intermediate fission- 
products, those within the same space being either all of one 
size (fig. 2, C) or of very different sizes. Other spaces may 
be seen still full and distended with Chlorochytrium, the 
constituent cells of which exhibit very different degrees of 
segmentation (fig. 2, A). Some have become resolved into 
the minute zoospores (tig. 2, B), while others have remained 
as fission-products varying much in size. Some writers 
have spoken of some of the larger forms as being probably 
* resting-spores.”’ 
It seems to me, however, that it can only with certainty be 
said that the Chlorochytrium cells undergo processes of divi- 
sion to a variable extent, so as to yield fission-products of 
very different sizes, and that, presumably under the influence 
of some unfavourable conditions in their environment, some 
of the products at each of these stages may undergo no further 
changes of a normal kind, and thus may never give rise to 
Chlorochytrium spores. 
This brings me to one of the important points which this 
communication is destined to make known, which is, that in 
the later stages of the life of Ch. Knyanum the fission-products 
within the intercellular spaces of the leaf are often found to be 
more or less intermixed with diatoms, varying not a little in 
size and in shape. 
This association is met with sometimes in spaces none of 
the contents of which have escaped, and then the contrast is 
great between the beautiful emerald-green of the algoid cells 
aud the brownish-yellow colour of the diatoms mixed there- 
with. At other times partially empty spaces are seen con- 
taining the fission-products of the alga alone (PI. XV. fig. 2,C), 
diatoms alone (fig. 2, D), or a mixture of the two kinds of 
units (fig. 3, A, B, C, D). 
* Loe. cit. Taf, iii. figs. 10, a, 5, ¢. 
Ann. & Mag. N. Hist. Ser. 7. Vol. xii. 12 
