1914) 
SCHRAMM—GRASS-GREEN ALGÆ AND ELEMENTARY NITROGEN 163 
nitrogen, and state that it is not possible to affirm with certainty 
that the alge, free from other organisms, are able to effect 
fixation. Having observed, however, but few bacteria in the 
cultures they conclude that the alge after all are the active 
agents in the fixation of elementary nitrogen. 
Similar results were obtained by Koch and Kossowitsch (17). 
Sixty grams of washed, calcined sand were placed in large Erlen- 
meyer flasks and moistened with a mineral nutrient solution 
free from combined nitrogen. Since previous experiments had 
shown that algæ do not grow on sand free from combined nitro- 
gen, 0.04 gram of calcium nitrate dissolved in 50 cc. of water 
were added to each flask. After inoculation with a suspension 
of algal cells obtained from heaps of lime, а continuous slow 
stream of air, washed in sulphurie acid, was passed through all 
the flasks. Three cultures were placed in a north window, three 
in the dark (to determine whether the bacteria contained in 
the cultures fixed free nitrogen), and the remainder were 
used in determining the initial total nitrogen. After fifteen 
weeks, during which time a rich algal vegetation! developed on 
all cultures exposed to the light, the contents of the flasks were 
analyzed in toto. Those exposed to the light showed an un- 
doubted increase in total nitrogen, whereas those in the dark 
showed a slight loss in each case. Of particular interest was one 
culture which was brought into the light after it had remained 
in the dark for a considerable length of time. After the removal, 
a moderate growth of alge appeared, and analysis showed a 
slight gain in total nitrogen, which, however, was less than that 
found in the cultures which had been exposed to the light during 
the entire period. In agreement with the earlier workers, these 
authors ascribed to alge the faculty of free-nitrogen fixation, 
and emphasized the observation that the extent of this fixation 
was directly proportional to the intensity of the algal develop- 
ment. Petermann (26) reached a similar conclusion on the basis 
of experiments conducted on sterilized and unsterilized soils, 
which were respectively inoculated and uninoculated with 
alge. The former in each case showed a distinct gain in nitro- 
gen, whereas the latter showed either no increase or a slight loss. 
1 The authors failed to state what асе developed, merely mentioning the presence 
of green and blue-green forms. 
