SECRETION OF DIASTASE BY PENICILLIUM CAMEMBERTII 253 
credence to the view that phosphorus and nitrogen are connected 
with diastase formation. The results secured with phosphorus are, 
however, hardly definite enough to allow one to draw conclusions very 
rigidly. The increased growth in the presence of nitrogen may also 
explain the increased secretion as the secretion per unit of dry weight 
of mycelium produced decreases with increasing concentration of the 
nitrates. 
Digestion in Nutrient Solutions 
The experiments on the influence of single salts revealed no evi- 
dence respecting the role of the elements in enzyme formation or 
secretion. It has already been stated that the absence of other salts 
might be limiting factors in the functioning of any given salt. Conse- 
quently, a series of experiments were performed to test the effect of 
the absence of various essential elements from the full nutrient solution. 
In the first experiment a modification of Richards's (1897) medium^ 
was employed. 
The salts substituted were used in the same concentration as the 
originals and the substitutions made were as follows : 
Minus nitrogen, KNO3, replaced by KCl 
potassium, KNO3, " Ca(N03)2 
KH2PO4, " " Ca(H2P04)2 
" phosphorus, KH2PO4, " " K2SO4 
" magnesium, MgS04, " " Na2S04 
" sulphur, MgS04, " " MgClo 
" iron, FeCls, " " NaCl 
Two series of experiments were performed, in one of which 50 cc. 
of solution and 0.4 percent of starch were used, and in the other 500 
cc. of solution and 0.8 percent of starch. Redistilled water was used 
as the solvent. The cultures were grown in triplicate in the dark 
at room temperature, and the time required for complete digestion 
of the starch was determined by daily tests of the culture medium 
by the method of Katz (1898). 
^ The medium used was composed of 
KH2PO4 5 g. 
MgS04 25 g. 
KNO3 . .1 
FeCls Trace 
Water 100 cc. 
Starch as indicated. 
