Notes on Freshwater Alger. 268 
in his monograph of the genus says, under Chloromonas 
( Chlamydomonas) variabilis, “ Gameten ? Zygote ? ” 
Chlamydomonas variabilis Dang, has been found by the writer 
several times in the Midlands, and was very abundant and 
produced numerous gametes in a small temporary pond in a meadow 
at Quinton, Birmingham, during February, 1918. The characters 
of the vegetative cells agreed very well with Wille’s description 
of the species, the form being more or less cylindrical, with a 
small anterior wart, and the chloroplast a parietal hand not quite 
extending either to the posterior or to the anterior extremities of 
the cell, so that a small hyaline space was left at both ends of the 
cell. No pyrenoid was present, but numerous minute starch grains 
were scattered throughout the chloroplast. The stigma was in the 
posterior third of the cell. The plane of the first division of the 
cell was exactly transverse. 
The first specimen taken from the pond showed that numerous 
gametes, many in process of fusion, were being produced (Fig. 2, E). 
The gametes are isogamous and much smaller in size than the 
vegetative cells. Size of gametes 8—10^ by 4’5—5/x (the vegetative 
cells were 15—22/x by 8—10/x). 
Morphologically the gametes resemble the vegetative cells, 
except that the stigma is located nearer the middle of the cell. 
They have no cellulose wall, being clothed only with a very thin 
protoplasmic membrane. Eight gametes are produced by each 
mother-cell. Fusion commences at the anterior ends of the two 
gametes and gradually extends posteriorly (Fig. 2, F, G.) 
Partially fused pairs of gametes are still actively motile, and even 
when completely fused, so long as the cilia are retained, the zygote 
(zygozoospore) is still motile. The four cilia of each zygote, 
however, are soon lost and a thin cell-wall secreted (Fig. 2, H). The 
two stigmas persist for quite a long time in the walled zygospore, 
but, as the contents of the latter become more granular, they 
gradually disappear. 
Zygospores were produced in hundreds and settled on the 
bottom of the wide-mouthed glass-jar into which the Alga had been 
placed. Some weeks after being formed numerous oil-globules 
appeared in the zygospores, the starch-grains gradually disappearing. 
The zygospore-wall remained smooth and colourless, and of moderate 
thickness. Width of mature zygospore 9—12/x. Their germination 
has not been observed. 
