1914) 
SCHRAMM—PURE CULTURE METHODS IN THE ALGJE 33 
of Stichococcus are soil-inhabiting and сап be obtained—practi- 
cally free from other algee—on flower pots and greenhouse soils. 
The former species, because of its minute cells and the readiness 
with which the filaments resolve themselves completely into 
their constituent cells when placed in water, is а particularly 
easy one to obtain in pure culture. Rich material may be 
diluted until plates obtained from it show a sufficiently small 
number of bacterial colonies to admit of pure transfers and 
yet enough algal colonies for a number of transfers. S. subtilis 
is a larger species and the cells remain attached in rather long 
filaments. However, with vigorous shaking and previous 
teasing apart with needles, a sufficient number of single cells 
and small fragments of filaments are introduced to make 
possible numerous successful isolations. Тһе washing of the 
cells to remove adhering bacteria can, in these species and 
many others, be largely accomplished by introducing the 
raw material into test-tubes containing sterile mineral nutrient 
solution or water, stoppering, and shaking vigorously. Direct 
transfers from these to liquid agar, or to tubes of sterile water 
for further dilution, may then be made. This procedure fre- 
quently enables one to make successful platings where the 
direct transfer of raw material to liquid agar results in constant 
failure. 
Chlorella vulgaris Bey., and Chlorella sp.—Both of these 
species were isolated from soil in the open. An exterior gelat- 
inous investment is, as in the two above mentioned species 
of Stichococcus, conspicuously absent, and preliminary experi~ 
ments demonstrated that a large number of the vegetative 
cells were freed from all accidentally adhering bacteria by being 
shaken in the liquid agar before plating. The problem of 
isolating these species again becomes one of clean material 
and sufficient dilution. Species of Chlorella are perhaps the 
easiest among the alge to isolate in pure culture, the process 
requiring little more than a direct application of bacteriological 
methods. 
Attention should be called to another method—really a 
modification of the one just given—by means of which Chlorella 
species may be obtained in pure culture. Its application is 
not necessary in the species of Chlorella investigated, since 
