1894. ] Anatomical and Physiological Researches. 289 
ized sand, in which an increase in nitrogen from 0.0024™ to 
0.0538" is noted. This experiment he regards as fatal to the 
theory of Hellriegel, inasmuch as this legume without tuber- 
cles on its roots can materially increase its nitrogen supply. 
2. The symbiotic microbe isolated from a leguminous 
plant thrives luxuriantly on organic N but barely lives when it 
derives its N from the air. 
In this view he is opposed more or less strongly by Praz- 
mowski,’? Laurent,1® Beyerinck,1® and Bertholot,?° all of 
whom maintain that pure cultures of the tubercle organisms 
take up quantities of uncombined nitrogen. 
3. The quantity of combined N in root tubercles does not 
suffice to account for the N in remaining plant organs 
He takes the analyses of five plants of Lupinus luteus and 
determines the N-content of the tubercles, the aerial organs 
and the roots proper and shows that at no time during the de- 
velopment of the plant do the tubercles contain more than a 
fraction of the nitrogen that is present inthe plant. Unless the 
tubercles yield up a continuous supply of N, which has never 
been claimed as taking place, it is hardly possible to account 
for the N supply of the plant unless the plant itself takes part 
in the assimilatory process. -As the samples selected were 
ta en from an open field, the conditions are such that the con- 
ee is hardly warranted that the plant itself assimilated a 
“re part of the nitrogen. Frank’s own experiment with this 
ime plant in sterilized soil (sand) only showed with six 
ei an increase from 0.042 in seed to 0.3475™ N in crop, 
: at the factor of soil and its organisms seems to be more 
mportant than anything else even in his own experiments. 
er The non-leguminous vegetable organisms can assimilate 
€ nitrogen. 
ea : show how wide spread is this function, he classifies ex- 
Ples under the following heads, including: 
@)‘tungi, quoting as an example a ten months’ culture 
of Penicillium cladosporioides in a nitrogen-free sugar 
Solution as fixing 0.0035 of N; 
(6) algze and mosses : 
(¢) phanerogams; 
*” Landw. Ve 
: - Versuchst, 38: 5. 1801. 
=i Inst. Past. 5: Vg ag 
toe ent. 52: 137. 1892. 
mptes rendus Acad. 16: 842. 1893. 
