[Vor. 1 
168 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
laris, and S. sp., the latter isolated from five different sources; 
Chlorella sp., from the group of which Chlorella vulgaris Bey. is 
typical (also isolated from five different localities); Chlorella 
protothecoides and three other isolations of a form or forms 
belonging to the same group; Chlorothecium saccharophilum and 
five other isolations of forms belonging to the same group; 
and lastly, Cystococcus humicola. The media employed by 
the authors included the following: 
1. One per cent dextrose, 0.2 per cent КзРО,, 0.04 per cent 
Mgs04, 0.02 рег cent CaCl», and 1 drop of a 2 per cent 
FeCl; solution to each 100 се. of solution. 
2. Ignited sand moistened with solution 1. 
3. Solution 1 plus 0.25 per cent (ХН.),5О,, and 0.25 per cent 
NaNO. 
4. Ignited sand moistened with solution 3. 
5. One-half per cent beef extract, } per cent peptone, and 1 per 
cent dextrose. 
Ignited sand moistened with solution 5. 
Diluted beerwort. 
Ignited sand moistened with solution 7. 
Humoüs clay soil plus 35 рет cent sand moistened with distilled 
water. 
есет 
The results obtained were uniform in that the media, free 
from combined nitrogen, failed to produce a healthy growth, 
whereas those containing nitrogen in a combined form showed 
an abundant growth,—some of the alge preferring the nitrogen 
in an organic and others in an inorganic form. Further, no fixa- 
tion of free atmospheric nitrogen was noted in any of the cultures. 
Krüger and Schneidewind conclude that there is a strong 
probability that all other chlorophyllous soil alge of this kind 
are unable to fix free atmospheric nitrogen, and, in general, 
agree with the opinion of Kossowitsch that the soil-inhabiting 
alge supply the free-living, nitrogen-fixing organisms with the 
necessary non-nitrogenous, energy-furnishing material. 
Conclusions similar to those of Kossowitsch were reached by 
Deherain and Demoussy (8), who succeeded in cultivating blue 
lupines free from root nodules in humus-free sand, the surface 
of which became covered with Phormidium autumnale and 
Ulothrix flaccida in the course of the experiments. The authors 
