g6 Gfiose. — A New Species of Uroncma from India . 
end cell was often found to be slightly thickened, and in a few cases the tip 
also ended in a dot-like thickening (Figs. 6 and 9). 
The remaining cells are cylindrical and vary very much in size. In 
young filaments they are longer than they are broad, while in mature ones 
they are broader than they are long. At the time of zoospore formation, 
the width of the filament becomes considerably increased, sometimes two 
or three times the width found in the vegetative condition. The cells of 
a mature vegetative filament usually range between 16 juto 22 /x in thickness 
and iOjut to 18/x in length (Fig. 10). A slight swelling is sometimes seen 
at the junctions of cells (Fig. 4). Each vegetative cell has a single band- 
shaped chloroplast, which runs through nearly the whole length of the cell 
and passes round about two-thirds of the cell circumference. Its edges are 
irregular and more or less incised. Pyrenoids up to four in number have 
been seen in some cells (Fig. 10). They are usually associated with 
numerous small grains of ‘ stroma starch ’. These grains are more con- 
spicuous in cells forming zoospores ; in fact they seem to fill up the whole 
cavity of the cell at that time. Chloroplasts are very easily seen by staining 
the filaments with gentian violet. There is a single nucleus in each cell. 
It is not easily seen as it is generally covered by the chloroplast. Only 
rarely is it seen lying near the centre of the cell (Fig. 10, 71). 
The chief method of propagation is by 4-ciliate zoospores. In 
younger filaments the whole cell produces a single zoospore, but as the 
filament grows the cells form transverse and longitudinal septa, thus 
making the filament multiseriate (Figs. 3 and 11)*. Each of the cells thus 
formed produces one zoospore. The escape of zoospores is similar to 
that found in Uronema elongatum 1 (Fig. 1 2). Sometimes, however, it was 
observed that a zoospore while coming out through the pore became con- 
stricted and finally divided into two. Thus two zoospores were produced 
from one cell without a septum being formed at first. The zoospore is 
nearly rounded and about 10 /x in diameter (Fig. 13). It is characterized 
by possessing abundant starch grains, which conceal the nucleus and the 
chloroplast. No pyrenoid was observed, perhaps also on account of its 
being concealed by the starch grains. Very soon after its emergence the 
zoospore becomes active and swims away. Germination takes place as 
in U. elo72gaium. 1 Sometimes two or three zoospores germinate together, 
and their basal mucous discs become confluent (Fig. 14). 
The chief interesting points about this alga are its great length and 
great variation in size. Sometimes the filament is packed with zoospores 
and attains a thickness of 40 /x (Fig. 15), while a young filament maybe only 
10 fi in thickness. Fig. 3 shows a filament about 13 ju in thickness, some 
cells of which are forming longitudinal septa also. Fig. 1 1 shows a part 
Hodgelts, W. J. : Uronema elongaium . New Phytologist, July 1918. 
