155 
explained by the formerly described mutation *) occurring under the 
influence of borie acid. 
From these observations it follows that the metabolism of- the 
carbon, in opposition to the velocity of the growth and spore pro- 
duction, changes little by the said chemical influences. 
3. Acton of copper. 
Whilst Ravin’), proved that coppersulfate in strong concentrations 
is noxious to the development of Aspergillus niger, Ricurur and Ono 
put the question whether copper in very dilute solutions may act 
favourably. 
ANDREAS Ricnrer ®), who stated that in absence of zine even addi- 
1 
tion of Tan gr.mol. coppersulfate per L. caused the weight 
of mould to decrease, answers this question negatively. 
N. Ono *) came to an opposite result. 
The observations of Ono and RicutER need not, however, be in 
contradiction with each other as it is not certain that they cultivated 
under the same circumstances, although Ono endeavoured to do so. 
Ono’s experiments especially are deficient in as much as the 
velocity and the nature of the metabolism are not sufficiently sepa- 
rated. For this reason I have once more made an analogous in- 
vestigation. 
The chemicals used were of KAuibaum’s and of great purity. 
The distilled water was once more purified by redistillation in an 
apparatus of Jena glass joined by a glass tube to a tin cooler’), and 
then kept for use in Jena flasks. The cultivation took place in 
ERLENMEYER flasks of Jena glass of 200 em°. capacity. 
The composition of the culture liquid was: 
0.15 °/, ammoniumnitrate 
0.1 ,, potassium-chloride 
0.1 ,, magnesiumsulfate (crystallised) 
0.05 ,, calciumnitrate (free from water) 
0.05 ,, fosforic acid (crystallised) 
2 ‚‚ glucose. 
1) H. J. WateRMAN, These proceedings, June 1912, Vol. XV, p. 124. 
2) Le. po 136. 
3) A. Ricuter, Centralbl. f. Bakteriol. Ze Abth. Bd. 7 (1901) p, 417. 
4) N. Ono. Centralbl. f. Bakteriol. 2e Abth. Bd. 9 (1902) p. 154. 
5) Corks and such like material were avoided. 
Jg 
Proceedings Royal Acad. Amsterdam. Vol. XV, 
