112 SIPHOPHYCEE. 
The following is » summary of Rostafinski and Woronin’s researches 
on this genus :— 
If a plant be placed in water, its contents become modified at the 
latter part of the day or at night into zoospores. Ultimately the wall 
swells, then bursts somewhere at the top, and the zoospores resulting 
from the division of the parietal stratum escape. If the plant be only 
moistened, the zoospores do not swarm ont, but come to rest within the 
collapsed wall. Such were known to previous observers as “germ 
cells” or “ gonidia.” 
The zoospores are elongate-oviform, 5-8 x 20 mm., with a single 
flagellum, and 2 to 4 chlorophyll granules. Having swarmed out, they 
soon come to rest, lose the flagellum, become surrounded by a mem- 
brane, increase in size, and germinate on’ damp earth, in which stage 
they represent the so-called Protococcus botryoides. 
The large ordinary zoosporangia are also otherwise modified. If one 
is allowed to dry, its membrane collapses, loses colour, and soon becomes 
empty. The protoplasmic contents pass down to the ramifications of 
the root. Here they break up into numerous cells, sometimes two or 
three side by side, but chiefly in a continuous chain ; each cell furnished 
with a separate membrane. 
These are capable of three forms of development :—(1) If removed 
from the soil and placed in water, the cell becomes a subterranean 
zoosporangium. The formation of the zoospores is independent of light 
at any hour of the day or night. The zoospores are similar to those 
above described, and germinate in the same manner. (2) If a chain of 
these root cells be laid on moist earth, each protrudes a hyaline process, 
which enters the soil, the opposite end being elevated, and thus each 
root cell becomes a vegetative plant. (3) If the root cells are not 
removed, and kept equably moist, they also germinate in the earth, 
become inflated, put forth a root process, the wall of which becomes 
very much thickened on the inner side below the inflated upper portion. 
By interculary growth of the root portion the upper part becomes raised 
aloft, so that the apex is carried above the surface of the soil. These 
products of modified root cells are named hypnosporanges, and are equi- 
valent to so-called Botrydium Wallrothiit. When dried, the hypno- 
sporanges retain their power of germination during the whole year, and 
when placed in water form zoospores at any hour of the day and night, 
germinating and forming young plants as above, 
The uniflagellate zoospores germinate on a moist substratum. On 
earth or sand they thrive badly, but better on clayey or muddy soil. In 
water they never germinate, but come to rest, are surrounded by a 
double membrane, and lie dormant for months. If these be transferred 
upon a clayey soil, they commence to form « vegetative plant. If the 
zoospores be sparingly distributed over the soil, and the whole kept 
equally moist, the vegetative plants become ordinary zoosporanges. The 
plants are sometimes modified into hypnosporanges. 
Thus, vegetative plants can be increased by cell division directly 
from zoospores, become ordinary zoosporanges, with such consequences 
as root cells, &c., or they may be directly modified into hypno- 
sporanges. But there is yet another way in which existence may be 
carried on. If exposed to drought, the following phenomena occur :— 
The wall collapses more or less, and the protoplasmic contents break up 
into a number of cells, each surrounded by a delicate membrane, its 
contents homogeneons, at first green, then passing into red. These are 
the spores, and have been known by such names as Protococcus coccoma, 
P. palustris and P. botryoides. These spores become changed in water 
to zoosporangia, their contents giving rise to zoospores in the manner 
already described. If the spores be still green, their zoospores will 
have a distinct fusiform figure, with two cilia at one end. They consist 
