ae ee eee ee eS ee, 
1893.] The Zoospores of Draparnaldia. 295, 
central transverse band of chlorophyll, containing several 
pyrenoids. On the sides of this axis and its main branches 
are borne numerous smaller branchlets, each itself branching 
copiously into a plumose tuft. The cells of these branchlets 
are shorter and their chlorophyll covers nearly the entire wall. 
Toward the end of the ultimate branchlets the cells are much 
longer, with the narrow chlorophyll band central. The 
young branchlet is tipped with a long hyaline multicellular 
The production of zoospores is confined to the branchlets, 
but to no particular part of them. Often the contents of all 
the cells of a branchlet become thus transformed, and it is 
hot uncommon to find a vigorous plant changed in a single 
day to a naked axis surrounded by the empty cell walls of its 
branchlets. 
The zoospore is ovate or oval in form (fig. 1) and averages 
about 12-16 x 8-104, though there is much variation in both 
form and size. The anterior end is rather pointed and nearly 
tyaline. On the tip are attached the four cilia, each rather 
— than the body. The chlorophyll is parietal, but not 
ones distributed, and contains one or more pyrenoids. 
aie 1S @ bright red pigment spot, lanceolate in outline and 
“Pparently slightly raised above the surface. It is usually 
eh about on the middle of the side of the zoospore, in a 
0 agg Position. It is always connected with the chromat- 
pire, and in one case was observed at the very base of the 
ly and tapidly contracted. Occasionally the contrac- 
four hours befor 
manner of its fo 
i i ne can 
often find a “wtieatingy could not be determined. O 
nchlet differing apparently in no respect from 
around it, except that each cell bears in some part of oe < 
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