VOLVOCINEE. 55 
GrEnus 38. CHLAMYDOMONAS,. Ehrd. (1833.) 
Macrogonidia ovate or oblong-rounded, green, delicately 
granulated, involved in a rather narrow byaline tegument 
frontal extremity very obtuse, or somewhat truncate, with a 
contractile vacuole, and two cilia; posterior extremity with a 
large chlorophyllose vesicle, and with or without a red lateral 
spot. Microgonidia arising from repeated division of the cytio- 
plasm of the macrogonidia, oblong or ovate, numerous, pale 
green or yellow, becoming brownish. Tranquil oospores glo- 
bose, red or brownish, contents firm, colourless, hyaline. 
“ Chlamydomonas is distinguished from Chlamydococcus by the closely 
applied membrane (not standing away from the contents) of the old 
swarming cells, also by the absence of the little starch-vesicles in the 
interior, while, however, as is usual in most of the Palmeilacee, a single 
large ‘chlorophyll utricle’ (starch utricle ?) exists in the interior. 
There is no central red nucleus, as in the gonidia of Chlamydococcus, 
but some species have a parietal red spot. The motion is affected by 
two cilia, as in Chlamydococcus. As in that genus, there is a growth of 
the gonidia during ‘swarming,’ which lasts over the day and night. 
There is alsoa formation of microgonidia. The species of this genus 
are doubtless very numerous, but the distinction of them among them- 
selves, as we!] as from the swarming cells of many other Alga, is very 
difficult without a complete acquaintance with the history of their lives. 
The species Chl. obtusa, occurs in the Rhine valley, near Freiburg, in 
sand pits, which are ovcasionally almost completely dried up in summer. 
The macrogonidia grow during their period of swarming from ‘016 to 
aimost ‘033 mm. long; they are longish, of equal diameter on both 
sides, and very obtuse, almost truncated, having a colourless place at the 
ciliated extremity, presenting the form of a notch. In regard to other 
points, the contents are dark green, finely granular, with a large vesicle 
at the posterior extremity, a roundish lighter space in front of this, and 
no red point. They multiply by simple or double halving in several 
successive generations. Sometimes a further continuation of the divi- 
sion of the full-grown macrogonidia occurs, forming sixteen or thirty- 
two macrogonidia from ‘005 to ‘008 mm. long, of ovate shape and 
lighter colour, tending towards brownish yellow. The resting cells are 
globular, about ‘025 mm. in diameter, at first green, subsequently light 
yellowish brown, finally flesh-red; they have a tough, colourless, and 
transparent membrane. Another species, Chl. tingens, occurs in enor- 
mous quantity in the puddles of the sandstone quarries at Lorettoberg, 
near Freiburg, in the month of March, in mild seasons sometimes even 
in January and February. The swarming cells are smaller than in the 
preceding, ‘008 to ‘016 mm. long, ovate, lighter green, likewise destitute 
of ared spot, and the membrane is more distinct in theoldage. In- 
crease by double, rarely by simple halving, in the former case with de- 
cussating sections, 
“Several species of this genus, previously included in the animal 
kingdom, but nearly allied to Gl@ococcus and Chlamydococcus, present 
themselves in the beginning of spring, in such abundance that they 
produce a striking green colouration of the water; a few weeks later 
they vanish, leaving no trace, and are not noticed again throughout the 
whole year.”—Braun Rejuvenescence, p. 215, 
