1914) 
SCHRAMM—PURE CULTURE METHODS IN THE ALGZE 48 
the cultural methods.  Zoóspores and zygospores, respectively, 
free from other organisms, were obtained in these cases but 
failed to develop in the cultural media subsequently supplied. 
There can be little doubt, however, that the latter difficulty 
will be overcome in time. 
Except in the Oscillatoriacee, little progress was made in 
the Cyanophycee. The problem appears especially difficult 
in the Coccogoneales where all forms of motile reproductive 
bodies are absent, and in which the vegetative cells apparently 
cannot be rendered free from adhering organisms by mechan- 
lica means. Even in the heterocystic Hormogoneales, the 
situation is a difficult one, the more slowly moving hormogonia 
apparently being unable to escape the bacteria.! While no 
experiments were made along these lines, it appears highly 
desirable to attack the problem in the latter group through 
the spore. It is well known that the spores of blue-green 
alge are extremely resistant to heat, and it does not appear 
improbable that the bacteria—especially if they are all in the 
vegetative condition—could be killed by heat, leaving the 
algal spores unharmed. Chemical sterilizing agents may also 
prove of value here. The latter may also prove serviceable 
with members of the Coccogoneales and certain of the grass- 
green alge which have thus far failed to yield to the technique 
employed. 
CONCLUSIONS 
1. By adapting methods of pure culture technique to indi- 
vidual species of alge, it has been possible to isolate in pure 
culture the following forms: 
Chlorophycee.—Chlamydomonas pisiformis Dill forma minor 
Spargo, Stichococcus bacillaris Näg., S. subtilis (Kütz.) Klercker, 
Ulothrix sp., Chlorella vulgaris Bey., Chlorella sp., Pleurococcus 
vulgaris, Scenedesmus sp., Kirchneriella sp., Chlorococcum humi- 
cola (Näg.) Rabenh., Protosiphon botryoides (Kütz.) Klebs, 
Stigeoclonium tenue (Ag.) Kützing, and a number of others 
of uncertain identity. 
1In a contribution which has just appeared (Kulturversuche mit Chlorophyll- 
führenden Mikroorganismen, III. Zur Physiologie der Schizophyceen. Beitr. z. Biol. 
d. Pflanzen 12: 49-108. 1913), Ernest G. Pringsheim reports the isolation in pure 
culture of a species of Nostoc. The method used was that of repeated transfers to 
sterile silicic acid jelly plates. 
