78 V. H. YOUNG 



lating and at the same time yield no enzyme capable of hydrolyz- 

 ing amygdalin. Such cultm-es when ''starved" on distilled water 

 produce a large amoimt of emulsin wdthin forty-eight hours. It 

 thus appears that emulsin is produced when sugar is the source 

 of carbon, even though no glucoside is present and that ammon- 

 ium nitrate in large amounts inhibits emulsin formation. Emul- 

 sin appears to be formed as the result of starvation. 



Went (1901), in a voluminous article on the influence of nutri- 

 tion upon the formation of enzymes in Monilia mophila, finds 

 that at least ten enzymes are formed by this fungus as follows: 

 viz., maltoglucase, trehalase, raffinase, invertase, cytase, amy- 

 lase, lipase, tyrosinase, trypsin and rennetase. All of these en- 

 zymes with the exception of trehalase are secreted into the cul- 

 ture medium and may be precipitated from it with alcohol, al- 

 though thej'' suffer some loss of activity in this process. Ac- 

 cording to the conditions imder which they are formed, Went 

 separates these enzymes into three groups: (a) those that are 

 found in at least small quantities when the fungus is grown on 

 any medium, (b) those that are formed onlj^ when certain sub- 

 stances chemically allied to their substratum are present, and 

 (c) those that are formed only when the particular substrate on 

 which they act is present in the culture medium. Enzymes 

 belonging to the first named class are tyrosinase, amylase and 

 invertase. Trypsins and rennetase belong to the third class. 

 The formation of rennetase is entirely dependent on the presence 

 of casein in the culture medium. Maltase is formed only when 

 carbohydrates are present and in addition a nitrogen-containing 

 salt. Proteins are in some cases able to stimulate the secretion 

 of the carbohydrate-splitting enzymes and Went suggests that 

 this may be due to the presence of the carbohydrate molecule in 

 them. When a substance causes the secretion of an enzyme the 

 increase of this substance into the culture medium causes an 

 increase in the secretion of that enzyme. Thus solutions up to 

 10% of dextrin, 5 to 10% of maltose, or 10% of rafhnose cause 

 an increase of enzym.e secretion. The author says that this in- 

 crease in secretion is not due to the increase in osmotic pressure 

 but does not explain the reasons for his belief. Trehalase is 



