Alga- like Organism . 381 
zoospore is very apt to have less of the chromatophore and 
may be even hyaline. 
The duration of the motile stage is but transitory. The 
zoospores settle down within a very few hours after their 
escape from the filaments, and attach themselves to some 
substratum preparatory to germination. When confined in 
a Van Tieghem cell, they immediately moved in straight 
lines to the edge of the drop of water nearest the light, and 
there attached themselves to the cover-glass. They come to 
rest on their ciliated ends, and the cilia may be seen to move 
over the substratum as the zoospores slowly revolve. The 
remains of the cilia are often present for some time after the 
zoospores have germinated. (See Figs. 6, 7, and 8.) 
After the zoospore is firmly attached to the substratum, 
a wall is formed around it which completely encloses the 
protoplasmic mass in a cell that is fastened to the substratum 
by a disc-shaped base. In many young plants, which de- 
veloped on the sides of the aquaria, the mass of protoplasm 
divided immediately (Figs. 9 and 10), but in most cases there 
resulted a curious sort of forward growth, unlike anything the 
writer has ever seen described among Algae. 
The cell begins to elongate very soon after the zoospore has 
surrounded itself with a wall, and, as it lengthens, the mass of 
protoplasm ceases to entirely fill the cavity, but moves upwards, 
always remaining closely applied against the wall of the upper 
portion. The lower portion of the cell-cavity is therefore left 
entirely free of protoplasm. Within a few hours after the 
zoospore has attached itself to the substratum, one notices 
a slight space between the mass of protoplasm and the base 
of the cavity (see Fig. 7, a plant twelve hours old). This space 
grows larger as the cell elongates, until finally it becomes about 
equal in length to the mass of protoplasm in the upper portion 
of the cell. 
The next change is very peculiar. The lower portion of 
the mass of protoplasm which before this had an undulating 
contour, becomes rounded off into a convex surface, and a wall 
is formed across the cavity. As a result there is left at the 
