INULASE FORMATION IN ASPERGILLUS 131 



effect unless we conceive of some ''antagonistic" relation between 

 the particles of the two substances, for which antagonism there 

 is at present no evidence. Evidently in the case of inulase, at 

 least, under the conditions of these experiments, the production 

 of the enz3^me is not a starvation phenomenon, but quite the 

 reverse and further, its production appears to be quite independ- 

 ent of the presence of glucose which, although causing an in- 

 creased growth of the fungus, does not affect the amount of 

 inulase produced. 



Previous investigators do not appear to have considered, to 

 any extent, the fact that closely related substances are more ef- 

 fective in stimulating the enzymes corresponding to the related 

 substances than are less closely related substances. Knudson 

 (1913) has shown that gallic acid in addition to tannic acid is 

 able to stimulate tannase production. The results here pre- 

 sented indicate that soluble starch is much more effective in 

 stimulating inulase production than glucose. It seems probable, 

 that the preliminary steps in enzyme production may be more or 

 less common for a number of enzymes and that the changes 

 which finally produce enzymes, affecting closely related sub- 

 stances, may be sufficiently alike to be affected to some extent 

 by closely related substances in the substratum. The results 

 obtained by Pottevin (1903) on the effect of the space relations 

 of various carbohydrates on the enzymes produced by fungi sug- 

 gests that a study of the effects of fructose and its derivatives 

 and of other hexose sugars might be of interest in relation to 

 inulase production. 



F. SUMMARY OF RESULTS 



1. Under all conditions studied inulase is produced by Asper- 

 gillus niger in appreciable quantities. 



2. Inulase is present in the fungus mycelium in greatest 

 amounts at the period of sporulation of the fungus and rapidly 

 disappears after that time. 



3. Inulase is produced in greater amounts by the fungus, when 

 inulin is present in the culture medium, but is also formed when 

 other carbohydrates are used as the sole source of carbon. 



