118 ARCHER, ON STEPHANOSPHZRA PLUVIALIS. 
The Family of Chlorospermatous Algie, Volvocinacee, to 
which this plant belongs, is characterised by the individual 
green cells, being, during the greatest part of their life, active 
zoospore-like bodies, ciliated, either solitary or combined into 
definite groups, and either with a common env eloping mem- 
brane, until breaking up in carrying out vegetative develop- 
mental processes, or without acommon membrane. With the 
exception of the genus Protococcus (Chlamydococeus), which 
is asingle cell, the cells, though thus for the greater part of 
their existence associated into colonies, maintain their special 
physiological individuality; and collectively, at the same 
time, represent but one individual in relation to external 
objects. With these general characters Stephanospheyra 
accords ; that is to say, it consist of colonies of ciliated cells 
which originate from a single mother-cell through a series of 
divisions following a definite law ; and, when completed, the 
colony possesses its own characteristic collective figure and 
organization. Here there are eight green masses of pro- 
toplasm—* primordial cells” (Cohn)—arranged circularly at 
regular intervals within a common hyaline membranous 
globe, so as to form an equatorial series. Hach primordial cell 
is furnished witha pair of flagelliform cilia, which protrude 
through the hyaline globe, and, by their action in the sur- 
rounding water, cause the active revolution hither and thither 
of the ageregate family, that is, of the Stephanospeera-globe. 
Regarding the direction of the wreath or series of eight 
primordial cells as the equator of the globe, the rotating move- 
ment is effected round the axis uniting its poles, and its 
vigorous onward moyement takes place in all possible direc- 
tions. 
Scarcely a more charming spectacle can be than a multitude 
of these elegant organisms vigorously rotating hither and 
thither, brigh tly green, and, under a peculiar light, glittering 
and flashing as they move, now showing a polar, now an 
equatorial view, or all interv ening positions, rapidly passing 
and repassing, curving, and w heeling ,and gyrating, crossing 
and recrossing each other, huddling and thro nging sometimes 
in numbers together, again starting off, occasionally rotating 
without advancing or “resting on their oars”—some larger 
and older, some smaller and younger, some showing young 
revolving Stephanospheerz within, some developing ‘ micro- 
gonidia,” some in one stage, some in another. In respect of 
beauty ‘and gracefulness, indeed, a number of the larger, 
gently revolving, emerald-studded globes of Volvox glo- 
bator, executing their elegant revolutions, must, I think, 
carry off the palm; but their numbers, and the amazing 
