82 V. H. YOUNG 



lie acid present in the substratum and in the absence of these 

 substances, no tannase is formed. 



Kylin (1914) has studied the regulatory formation of certain 

 enzymes in Penicillium glaucum, P. bifor7ne and Aspergillus niger. 

 Investigations were made on the effects of carbohydrate nutri- 

 tion on the formation of diastase, invertase and maltase. Kylin 

 finds that the work of Katz along similar lines is not without 

 certain defects since he did not consider the reaction of the cul- 

 ture medium or the changes that took place in it during the 

 growth of the fungi. Kylin believes that the acidity arising when 

 glucose is present in the culture medium and the alkalinity aris- 

 ing when ammonia is set free in cultures containing asparagin 

 hinder the action of enzymes produced by the fungus and thus 

 a true index of enzyme formation is not obtained. In no case 

 does Kylin find any evidence of qualitative enzyme regulation, 

 but quantitative enzyme regulation has been noted in a great 

 number of cases. With Aspergillus niger diastase is formed v/hen 

 no starch is present, — maltose, quinic acid, mannitose, glycerin 

 and peptone, being used in its stead. Small amounts of starch 

 added to such cultures cause a large increase in the amount of 

 diastase formed and, if the fungus is grown with starch as the 

 only source of carbon, the amount of diastase produced is still 

 greater. Dextrin is found to be quite as efficient as starch. 



The results obtained by Kylin in his work on diastase forma- 

 tion in Penicillium glaucum are in general similar to the results 

 obtained with Aspergillus niger. Small amounts of glucose 

 (0.2%), together with starch, cause an increase in the amount of 

 diastase produced, but if as much as 5% of glucose be added, a 

 decrease in diastase production results. The regulatory secre- 

 tion of diastase in PeyiicUlium glaucum is more marked than in 

 Aspergillus niger. 



In his work on invertase formation of Aspergillus niger, Kylin 

 corroborates the results obtained by Colin (1911) on the effect 

 of glucose. This substance is found to have no influence oh the 

 amount of invertase produced. Invert sugar is likewise shown 

 to be without effect. Kylin further finds that, when sucrose is 

 present in the culture medium, the formation of invertase is 



