[Vor. 1 
32 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
SPECIFIC 
CHLOROPHYCEJE 
Chlamydomonas pisiformis Dill forma minor Spargo.— 
Chlamydomonas species frequently occur in water rich in organic 
materials, and teeming with bacteria. When the alga was in the 
resting condition, the mucilaginous сей walls were found so 
impregnated with bacteria as to render isolation in pure culture 
impossible. Platings with motile cells, however, showed that 
the latter were absolutely free from regularly adhering bacteria, 
but the number of bacteria present rendered the plates worth- 
less. Then the gelatinous masses of resting cells were repeat- 
edly washed with sterile water and finally placed in distilled 
water where, after twelve to twenty-four hours, zoóspores 
appeared in great abundance and congregated on the side 
of the vessel nearest to the light. А minute portion of 
this liquid containing the zoóspores was removed with a fine 
capillary tube and introduced into a tube of liquid agar and 
plated. In platings thus made, numerous colonies of Chlamydo- 
monas appeared and the number of bacterial colonies was so 
small that a large number of successful pure transfers were made. 
Where the number of available motile cells is small and it 
is important that isolations be made from these, a modification 
of the method used by Barber (3) in the isolation of yeasts 
and bacteria was frequently used to advantage. А large num- 
ber of small, capillary pipettes were made and sterilized. After 
locating the cell or cells desired, they were removed with a 
pipette while being observed under the microscope, and trans- 
ferred to a drop of sterile nutrient solution or water. This 
process was repeated until it was certain that the number of 
bacteria had been reduced sufficiently to admit of successful 
plating. They were then taken up again by means of a sterile 
pipette, transferred to a tube of liquid agar, and plated. 
Numerous pure cultures were obtained in this way. 
Stichococcus bacillaris Nág., and S. subtilis (Kütz.) Klercker.— 
Preliminary platings with these forms showed that the cells, as 
obtained from the soil, yielded abundant bacteria-free colonies, 
and the problem of isolation became one of merely obtaining 
clean material and diluting sufficiently. Both of these species 
