220 



of organlc foodmatenal. Pfeff er on the other hand, in the same 

 year, expressed as his opinion that as a rule, organisms accomodate 

 their enzymes to the foodmatenal, which is présent. If Aspergdlus 

 niger is cultivated on a mixture of starch and glucose, it will secrète 

 amylase only then, when the glucose has been consumed and the 

 only foodmaterial, avallable for the fungus, is starch. 



In the laboratory of Pf ef f er,and also in the expenments of Katz, 

 who made a more detailed investigation in 1898, the fungi {Asper- 

 gillus niger and Pénicillium glaucum) were cultivated on several 

 kinds of sugar, always with the addition of starch, usually 0.25*^0. 

 He observed, that the présence of the sugars diminishes the pro- 

 duction of amylase, and that this decrease is direct proportional to 

 their concentration. In the case of Pénicillium even a low sugar- 

 concentration is enough to stop the sécrétion of amylase entirely. 

 He finds that diastase is produced, even when glucose is the only 

 organic food présent This was the first time that a quantitative 

 modification of enzyme production had been observed. 



It is rather a pity that Kat.'. was satisfied with investigating from 

 day to day whether there was any starch left in the culture liquid; 

 if the lodine reaction was négative, the experiment was not con- 

 tinued. A single observation of the culture on glucose was enough 

 for him to draw his conclusions. 



Duclaux as early as 1899 remarked that Aspergillus niger and 

 Pénicillium glaucum produce many enzymes, but that nutritio;: 

 côuld be said to influence their sécrétion only within very wide 

 limits. Went in 1901 came to similar conclusions. He found ten 

 enzymes in the case of Monilia sitopkila. Thèse he divided into 

 three groups according to the influence that nutrition had on their 

 sécrétion : one group was always présent, no matter what culture 

 média were used; another group which was not formed in ail 

 média, but in several of them, and a third group of specihr: en- 

 zymes, which were only formed when the matenals acted upon by 

 thèse, were supplied in the culture médium of the fungus. 



Butkewitsch too observed, that foodmatenals had some in- 

 fluence on the quantity of the enzymes produced. As, however, 



