1047 
Microbiology. — “Metabolism of the nitrogen in Aspergillus niger.” 
By H. J. Waterman. (Communicated by Prof. M. W. Brierinck). 
(Communicated in the meeting of November 30, 1912). 
In a previous communication *) [| described the circulation of the 
earbon in Aspergillus niger. 
The changes which the plastic aequivalent or assimilation quotient 
of the carbon and the respiration- or carbonic acid aequivalent 
underwent in the course of time gave a clear view into the meta- 
bolism. In the beginning of the development a great plastie aequi- 
valent was constantly found, which, however, lowered quickly, 
whilst the carbonic acid aequivalent rose considerably in the course 
of time. 
The curve indicating the change of the two aequivalents with 
time could not be explained by an adsorption of nutrient substance. 
The existence of an adsorption, that is to say, a change of con- 
centration caused by molecular attraction of the components at the 
surface of a liquid formed by these components, gas, ete. and theo- 
retically foretold by W. GiBBs and J. J. THomson, has in many cases 
been experimentally confirmed. For such experiments it was desirable 
to artificially enlarge the surface, for example by formation of 
scum, in order to bring the phenomenon within the reach of the 
relatively rough methods of observation. 
Animal and plant cells present a great surface in relation to their 
contents. So it might be possible experimentally to observe the 
adsorption by the disappearance of the food from the surrounding 
medium. 
The above investigation, however, has proved that this is not the 
ease and the following experiments confirmed this. 
A living mould culture, some months old and washed out with 
distilled water, ca. 300 mers. dry and containing hardly any more 
glykogen, was during half an hour shaken with 50 em* solution 
of 2°/, glucose, 0,15°/, ammoniumnitrate, 0,15°/, KH,PO,, and 0,06°/, 
magnesiumsulfate in tapwater. The mould laver, which had absorbed 
hardly any glucose from the solution, was then repeatedly washed 
out with distilled water at room temperature, boiled for ten minutes 
with distilled water, then filtered. The filtration did not reduce 
“Fehling”, consequently contained no glucose. 
If the concentration of the glucose in the mould were likewise 
1) Folia microbiologica, Holländische Beiträge zur gesamten Mikrobiologie. 
Bd. 1 p. 422. 
