INFLUENCE OF CERTAIN SALTS AND NUTRIENT SOLU- 
TIONS ON THE SECRETION OF DIASTASE BY 
PENICILLIUM CAMEMBERTIL 
William J. Robbins 
Much has been pubHshed in recent years concerning the regulatory 
production of enzymes, but the investigations have been largely 
confined to the influence of the organic compounds on the production 
and secretion of enzymes. Little attention has been devoted to the 
effects of the mineral elements on enzyme formation. It would seem 
that such studies are of importance for several reasons. They might 
lead, for example, to a better understanding of the origin of enzymes. 
They should lead also to a clearer realization of the roles played by 
the mineral elements in plant nutrition. In this regard it is significant 
that there exists a relation between potassium and carbohydrate 
formation in green plants, and also a relation between calcium and 
starch translocation. The roles played by potassium and calcium 
in these processes are not understood, but it is possible, and it has 
been suggested by some investigators, that they condition the forma- 
tion of certain of the carbohydrases. 
It is also conceivable that studies of the effect of mineral salts 
on the secretion of enzymes would be important in the realm of plant 
pathology, particularly in the problem of disease resistance in plants. 
The interpretation of the action of distilled water on plants may also 
be aided by such studies. 
As a result of these considerations a problem was evolved compre- 
hending an investigation of the influence of certain single salts, and of 
certain nutrient solutions with various modifications, on the secretion 
of diastase by Penicillium camembertii Thom. The modifications 
of the nutrient solutions consisted in the replacement of certain 
essential radicals of salts by nonessential radicals. ^ 
1 Contribution, Laboratory of Plant Physiology, Cornell University. 
2 It is a pleasure to acknowledge the indebtedness of the author to Dr. Lewis 
Knudson for suggesting this problem, and for constant aid and assistance in the 
preparation of the manuscript. 
234 
