Annals 
of the 
Missouri Botanical Garden 
Vor. I MAY, 1914 No. 2 
A CONTRIBUTION TO OUR KNOWLEDGE OF THE 
RELATION OF CERTAIN SPECIES OF GRASS- 
GREEN ALGÆ TO ELEMENTARY NITROGEN 
JACOB R. SCHRAMM 
Assistant to the Director of the Missouri Botanical Garden 
Instructor in the Henry Shaw School of Botany of ` 
Washington University 
А general survey of the literature pertaining to the relation 
of alge to free atmospheric nitrogen reveals the fact that com- 
paratively few forms have been experimented with under 
conditions which render the conclusions reached free from 
objection. Тһе principal fault which may be found with most 
of the work done is that the experiments were carried out with 
impure cultures. Representatives from not more than four or 
five genera of green alge have thus far been studied in pure 
eulture, and while the general conclusion reached is that these 
forms are unable to fix free atmospheric nitrogen either in the 
presence or in the absence of combined nitrogen and energy- 
furnishing materials, it is by no means certain that forms do not 
exist which, under one or all of these conditions, are able to 
utilize elementary nitrogen. This thought is especially justified 
when the small number of free-nitrogen-fixing species among 
the bacteria is considered. In the present investigation, there- 
fore, an attempt has been made to extend the observations over 
a greater variety of forms in pure culture, —understanding by the 
latter a single species of alga free from all other organisms. 
ANN. Мо. Вот. GARD., VOL. 1, 1914 (157) 
