258 
WILLIAM J. ROBBINS 
fore, due to a decreased secretion of diastase. As was found with 
the single salts, the presence of salts decreases the secretion of diastase. 
Summary 
I. A method of determining diastatic action in solutions of soluble 
starch by the precipitation of the undigested starch and a part of the 
dextrins in acid alcohol is described. 
II. The addition of the chlorides and the sulphates of potassium, 
sodium, calcium and magnesium, singly, to a solution of Merck's 
soluble starch in distilled water treated with carbon black, decreases 
the amount of starch digested by Penicillium camembertii when the 
salts are present in M/io,ooo and M/i,ooo concentrations. 
III. The nitrates of potassium, sodium, calcium, and magnesium, 
when present singly in M/i,ooo, M/io,ooo, and, in the case of the 
nitrates of calcium and magnesium, in M/ioo,ooo concentrations, in 
a solution of Merck's soluble starch in distilled water treated with 
carbon black, increase the amount of starch digested by Penicillium 
camembertii. 
IV. The addition, singly, of the nitrates of potassium, sodium, 
calcium, and magnesium to a solution of Merck's soluble starch in 
distilled water treated with carbon black, decreases the amount of 
starch digested by Penicillium camembertii per unit of dry weight 
of mycelium when the salts are present in M/i,ooo, M/io,ooo and 
M/ioo,ooo concentrations. 
V. The dihydrogen phosphates of sodium and potassium, with the 
exception of M/i,ooo KH2PO4, do not decrease the digestion of starch 
when present in M/i,ooo, M/io,ooo and M/ioo,ooo concentrations. 
VI. Potassium salts inhibit the digestion of Merck's soluble 
starch in distilled water treated with carbon black more than do 
sodium salts. 
VII. A marked difference is noted between the speed with which 
Aspergillus Oryzce and Penicillium camembertii digest soluble starch 
in the absence of all added nutrients, and the rate of digestion by 
Mucor Rouxii and Fusarium sp. 
VIII. No evidence was found to connect potassium and calcium 
with diastase formation. 
IX. Nitrogen may bear an intimate relation to the formation of 
diastase by PeniciUium camembertii 
Cornell University, 
Ithaca, N. Y. 
