1914] 
SCHRAMM—GRASS-GREEN ALGJE AND ELEMENTARY NITROGEN 159 
gen and that the latter depends оп an inorganic process, the inor- 
ganic compounds thus produced being subsequently assimilated 
by the algz, is not rendered probable by later experiments. In 
these, Frank exposed samples of soil, kept free from vegetation, 
for long periods of time and at various temperatures. Plant 
growth was prevented by leaching the samples daily with hot 
water. In this manner any traces of nitrogen compounds 
formed were also obtained. Only at high temperatures—too 
high for plant growth—did he find a slight increase in total 
nitrogen and therefore believes that this process is of no impor- 
tance under conditions which admit of plant growth. From 
these observations Frank concludes that the alge themselves 
are the immediate agents in the fixation of free atmospheric 
nitrogen and inclines to extend this faculty to green plants in 
general. 
In the same year, Gautier and Drouin (11) ascribed an entirely 
different function to soil alge. Samples of artificial soils, free 
from organic material and containing only ammoniacal nitrogen, 
were exposed in a sheltered position for a considerable period of 
time. During the progress of the experiments the soil became 
more or less covered with a layer of green alge (Pleurococcus 
vulgaris, Protococcus viridis, etc.). Analysis showed, in every 
case, а loss in total nitrogen, an even greater loss іп ammoniacal 
nitrogen, and an intermediate gain in organic nitrogen. The 
authors assumed that the nitrogen lost was in the form of 
ammonia and that the amount of nitrogen appearing in the 
organic form was that part of the escaping ammoniacal nitrogen 
which, in bathing, so to speak, the algal cells on the surface, was 
absorbed, and subsequently built into organic nitrogen com- 
pounds. In support of this hypothesis the authors state that 
in proportion to the intensity of the algal growth loss in total 
nitrogen was diminished, and the amount of ammoniacal nitro- 
gen converted into organic nitrogen increased. Gautier and 
Drouin thus looked upon the alge as fixers of gaseous ammonia, 
which the soil tends to give off constantly, rather than as direct 
agents in the fixation of free atmospheric nitrogen. 
In 1889, Frank (10) made the fixation of elementary nitrogen 
by soil-inhabiting alge the subject of a special investigation. 
Four flasks containing sand moistened with distilled water and 
