282 MR. G. S. WEST ON SOME CRITICAL GREEN ALGE. 
irregular form, being situated in the anterior region of the cell. When 
more than one vaeuole exists, thev are commonly spherical. They contain 
a colourless cell-sap, and in all the specimens examined granules of а brown 
colour were present, which exhibited a lively dancing movement (figs, 7, 9-11, 
18, 19). These granules varied in number from 2 to 15 in each vacuole, and 
were of various sizes. They strongly reminded one of those formed in the 
vacuoles of most. Desmids under pathological conditions !. 
The nucleus is situated anteriorly, but may be displaced by the formation 
of a large vacuole. 
The horns are colourless and very hyaline, but as the eytoplasm of each 
process can be stained up to its extremity, they are hollow. 
А pair of long cilia are attached to the anterior extremity, and аз the 
organism progresses in a forward direction, it rotates about its longitudinal 
axis. This rotation is not constant, as the organisms, when examined on а 
slide, frequently come to rest and then begin again their movements, when, 
as often as not, they rotate in the opposite direction. 
The rate of movement was measured in a number of full-grown vegetative 
cells, and it gives an average of 022 mm. per second, which is considerably 
below the average for the Chlamydomonadew. 
When at rest the cilia are carried. backwardly directed. with the proximal 
part of each cilium closely pressed against the anterior margin of the cell 
(fig. 9). 
Several cultures of this organism were started in February and examined 
constantly up to Мау. Some were in Knop’s solution, and others in Knop's 
solution to which a small quantity of sodium chloride had been added. The 
tube of material as forwarded to me was a pure collection, and the most 
diligent search brought to light no other organism among the Brachiomonas. 
A few drops of this fluid containing the living Brachiomonas were added to 
about 150 e. e. of the prepared medium, so that no trace of colour could be 
observed in the culture, The glass eulture-vessels were exposed to the 
outside air temperature, except during frost. All the cultures became 
decidedly green at the beginning of April, but there was a marked difference 
in the two series. Those cultures from which sodium chloride was excluded 
contained hardly any Brachiomonas, but a species of Chlamydomonas and a 
multitude of rounded green cells in the palmelloid condition ?. 
Those containing sodium chloride were pure cultures of Brachiomonas, and 
the multiplication was carried on with moderate rapidity by the formation of 
zoogonidia. Four of these arose in each mother-cell, and they assumed the 
peculiar form of the adult before liberation. 
' Consult G. S. West, in Journ. Linn. Soe., Bot. xxxiv. (1899) pp. 401, 402, 
* I have been unable to determine with any degree of certainty the species of Alga to 
which these belong. Most of the Chlamydomonadex are known to assume a palmelloid 
state under certain conditions, but I hesitate to refer the above-mentioned cells to 
Brachiomonas, 
