28 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
from I to 12.5 mg., representing increases in the total nitrogen content of the 
culture flasks of from 4 to 54 percent. 
. 2. Five of the above mentioned species were grown on ammonium 
nitrate and calcium nitrate in the absence of glucose. Four of these showed 
slight increases in nitrogen over the original content of the medium; growth 
in the absence of glucose, however, was slight. 
3. There was no fixation when urea, glycocoll, asparagine, or ammonium 
sulphate was supplied as a nitrogen source, either in the presence or in the 
absence of glucose or of mannite. 
4. One species (no. 11) exhibited what is apparently a denitrification on 
media containing either ammonium nitrate or calcium nitrate as nitrogen 
sources, both in the absence of an organic carbon source and in the presence 
of mannite. The loss in nitrogen amounted to from 2.2 to 8.3 mg. per 100 
grams culture medium. 
Acknowledgments 
The writer wishes to express his sincere appreciation to Dr. J. R. 
Schramm, whose many helpful suggestions and constant interest have been 
invaluable aids in the completion of the experiments, to Dr. L. W. Sharp 
for the photographic work, and to other members of the department for 
kindly assistance in many ways. 
Department of Botany, 
New York State College of Agriculture, 
Ithaca, New York 
LITERATURE CITED 
Beijerinck, M. W. The significance of the tubercle bacteria of the Papilionaceae for the 
host plant. Kon. Acad. Wetensch. Amsterdam (English ed.) 21: 183-192. 1918. 
Charpentier, P. G. Alimentation azotee d'une algue. Le Cystococcus humicola. Ann. 
Inst. Past. 17: 321-334. 1903. 
Duggar, B. M., and Davis, A. R. Studies in the physiology of the fungi. I. Nitrogen 
fixation. Ann. Mo. Bot. Card. 3: 413-437. 1916. 
Fred, E. B. A physiological study of the legume bacteria. Ann. Rept. Va. Agric. Exp. Sta. 
1911-12: 145-173- 1912. 
Fred, E. B., and Graul, E. J. The effect of soluble nitrogenous salts on nodule formation. 
Jour. Amer. Soc. Agron. 8: 316-328. 1916. 
Freudenreich, E. von. Ueber stickstoffbindende Bakterien. Centralbl. Bakt. II. lo: 
514-522. 1903. 
Gerlach, M., and Vogel, I. Weitere Versuche mit stickstoffbindenden Bakterien. 
Centralbl. Bakt. II. 9: 817-821, 881-892. 1902. 
Hills, T. L. Influence of nitrates on nitrogen-assimilating bacteria. Jour. Agric. Res. 12: 
183-230. 1918. 
Hoffmann, C, and Hammer, B. W. Some factors concerned in the fixation of nitrogen 
by Azotobacter. Univ. Wis. Agric. Exp. Sta. Res. Bull. 12: 155-172. 1910. 
Kossowitsch, P. Untersuchungen iiber die Frage, ob die Algen freien Stickstoff fixiren. 
Bot. Zeit. 52: 97-116. 1894. 
Kruger, W., and Schneidewind, W. Sind niedere, Chlorophyllgrune Algen imstande, den 
freien Stickstoff der Atmosphare zu assimilieren und den Boden an Stickstoff zu 
bereichern? Landw. Jahrb. 29: 771-804. 1900. 
