82 THE PHYLOGENY OF THE GENUS BRACHIOMONAS 
polarity may be transmitted: for, as stated above, the third 
plane appears to cut the four daughter portions transversely 
in such a manner that half of the resulting eight would retain 
the original anterior cytoplasm, while the four posterior zoospores 
would seem to be under the necessity of regenerating (so to 
speak) their anterior pole. It is possible that in the slight 
shifting of the daughter portions following so quickly upon the 
first two divisions there is actually more rotation than is apparent 
so that the third division may effect a properly qualitative 
bipartition, but that appears doubtful from the cases observed. 
The whole problem of polarity in chlamydomonads is one of 
great interest demanding a degree of care in observation which 
hardly any species up to the present has received. 
Brachiomonas simplex sp. nov. 
This species was first discovered at Aalesund, Norway, in 
the last days of June 1920, and was also collected three weeks 
later at Cullercoats, near Newcastle-upon-Tyne, and in August 
at Plymouth, England. It was found in small rock pools of 
brackish water, sometimes in association with one of the other 
species of Brachiomonas, then again in practically a natural 
pure culture. 
At first sight the organism looked like a Chlamydomonas, 
many individuals (Fics. 31, 39) showing somewhat the general 
oval, posteriorly pointed form characteristic of C. caudata 
Wille (Fics. 46-50), which occurred near by, though never in the 
same pools. But presently it was noticed that even the cells 
most nearly approaching C. caudata in form were nevertheless 
more like Brachiomonas submarina in internal organization, 
showing a similar linear stigma and large lateral and anterior 
pyrenoid; furthermore many individuals show small bumps or 
protuberances slightly back of the middle region, immediately 
suggesting the arms of Brachiomonas, though never really at- 
taining that character (Fics. 28, 29). The posterior horn, often 
rather elongated, shows a characteristic curve not seen in B. 
submarina. Generally the protoplast was conspicuously fur- 
nished with vacuoles, but whether this is a constant character 
is somewhat doubtful, inasmuch as C. caudata in similar pools 
was often similarly vacuolate at this time. The English ma- 
terial, moreover, was much less vacuolate. There is great 
variability in the development of the lateral protuberances; if 
formed at all they appear before the escape of the zoospores 
