215 
greatest for the perihelion, smallest for the aphelion. As a mean 
value of all these times we may consider 
3 
r= r(1— “). 
2p 
For this time Keprer’s third law becomes 
2 \3 
ae a 
De - Ft == : 
1—e? 82x? 
This deviates from KEPLER’s law less than (43). 
Chemistry. — “The Metabolism of Aspergillus niger.” By Dr. H. J. 
WATERMAN. (Communicated by Prof. J. BöESEKEN.) 
(Communicated in the meeting of May 27, 1916.) 
In researches described in previous communications ') I have 
demonstrated that the quantity of different elements accumulated in 
the cells of Aspergillus niger is subject to very great variations. The 
investigation was carried out quantitatively for carbon, nitrogen and 
phosphorus and qualitatively for the element sulphur. Whereas from 
100 parts by weight of carbon, assimilated as glucose, 55 parts, for 
instance, are absorbed after three days in the fungons material, this 
after 21 days amounts to only 31, so not quite 60°/, of the quantity 
originally taken up. The same applies to the nitrogen and parti- 
cularly to the phosphorus in a still higher degree. 
The quantity of nitrogen present in the cells falls in course of 
time to */,—'/, of the quantity present in the young cells and with 
phosphorus even to ‘/,—'/,,. Also the sulphur is accumulated in 
young cells. On increasing age the superfluous quantities of the 
said elements are excreted. 
On account of experimental difficulties I have given up the idea 
of determining the progressive course of the hydrogen and the 
oxygen separately, but have now decided to calculate the sum of 
these two elements accumulated in different periods in the fungous 
material. For, if we know the quantity of dry substance, likewise 
the percentage of carbon, nitrogen, phosphorus and ash, it is possible 
to determine with sufficient accuracy for my purpose the joint 
amount of hydrogen and oxygen. 
1) Folia microbiologica, Holländische Beiträge zur gesamten Microbiologie I, 
422 (1912); These Proceedings November 30 (1912) p. 753, February 22 (1913) 
p. 1047 and 1058, March 22 and April 25 (1913) p. 1349; Handelingen X1Ve 
Ned. Natuur- en Geneesk. Congres p. 125. 
