1913] CURRENT LITERATURE 89 | 
of yield with increasing concentration of the metal. An increasing quantity 
of the metal was found in the ash, although even in dilute solutions the element 
was not removed quantitatively, like calcium or zinc. A concentration of 1 
part in 50 was deleterious. 
Unexpected results® showing the sensitivity of plants to extraordinarily 
minute traces of substances were obtained with manganese in extreme dilutions. 
After every available means had been used for removing manganese from the 
ingredients of the culture solutions, it was found that the addition of 1 mg. of 
manganese in 1,000,000 liters produced a marked increase in yield, while in 
some cases even the effect of 1 mg. in 10,000,000 liters was noticeable. The 
effect of manganese in such extreme dilutions is attributed to action of a 
catalytic nature. The necessity of taking into consideration in physiological 
experiments the possibility of effects being produced by such minute traces of 
substances which may be present as impurities in the materials used is pointed 
out. 
The simultaneous addition™ of zinc and manganese in concentrations at 
which these metals individually increase the yield of fungus produces a greater 
yield than the addition of either metal alone. The favorable concentrations 
were: zinc, I part in 100,000 to 1 part in 25,000,000; and manganese, 1 part 
in 500 to r part in 2 
To determine if shee of these two. metals exerted an ‘alenos on the 
absorption of the other, the quantity of manganese absorbed in the presence of 
zinc was compared” with that absorbed from solutions without zinc. 
results show that in general the percentage of manganese in the dry weight of 
the fungus is greater in the presence of zinc. The proportion varies somewhat 
according to the concentrations of manganese and zinc. The effect of the zinc 
is more marked in dilute solutions and disappears in more concentrated 
solutions. 
To manganese is attributed a special réle in spore-formation formerly 
ascribed by RAULIN and by SauToN toiron. The effect noted by these inves- 
tigators BERTRAND® believes to be due to the introduction of minute traces of 
manganese from which it is difficult to free some of the other salts used in 
RAULIN’s solution. He finds that when Aspergillus is grown in a solution free | 
from manganese, but containing both zinc and iron (1 part in 100,000) no 
% BERTRAND, G., Extraordinaire sensibilité de l’Aspergillus niger vis-A-vis du 
manganése. Compt. Rend. 154:616-618. 1912. 
™ BERTRAND, G., et Javittier, M., Influence combinée du zinc et du manganése 
sur le développement de P Aspergillus ma gh eee 2s Rend. 152:900-902. I91T; 
also Bull. Sci. Pharmacologique 18: 321-327. 
u——.. Influence du zinc et du mangan ie sur la composition minerale de 
cn phar niger. Compt. Rend. 152:1337-1340. IQII. 
RAND G., Sur le réle capitol du manganése dans la formation des conidies 
de Serco niger. Compt. Rend. 154: 381-383. 1912. 
