INULASE FORMATION IN ASPERGILLUS 129 



relation to inulase. Within very restricted limits an increase in 

 the amount of inulin present causes an increase in the amount of 

 inulase formed. Thus, as is shown in table 5, 0.1% and 0.2% 

 of inulin in the culture medium results in equal inulase produc- 

 tion, but an increase to 0.4% of inulin results in a shght increase 

 in inulase production, which is by no means double the produc- 

 tion in the first two cases. Again in table 8 it will be seen that 

 0.1% inulin in the presence of 1.9% glucose has no effect beyond 

 the enzyme production with glucose alone. Evidently, under 

 the conditions of these two experiments, 0.2% of inulin is below 

 the minimum for the stimulatory effect of this substance, while 

 0.4% is somewhat above it. The results shown in table 6 reveal 

 the fact that, between the effects of 1%, 1.5%, and 2% solu- 

 tions of inulin, there is no significant difference so far as the 

 stimulation of inulase production goes. These concentrations 

 are evidently all above the maximum strength which will cause 

 increase in inulase production. The maximum and minimum 

 points for the stimulation of inulase production by inulin seem 

 to lie between 0.4% and 1%. It must be said, however, that it 

 would be very desirable to have a much greater amount of data 

 on this point than is presented in this work. That such an 

 increase of inulase production exists and that it lies within rather 

 narrow limits is undoubtedly the fact, but more data are needed 

 to establish these points more definitely. 



Many investigators believe enzyme production to be a ''hunger 

 phenomenon," while others have found that enzymes are pro- 

 duced more abundantly under more favorable conditions of nu- 

 trition. On theoretical grounds, one might expect the former 

 to be true. Evidently, however, one must discriminate between 

 at least two phases of ''hunger." If an organism is in the pres- 

 ence of only a limited amount of food material, its growth will 

 be limited by the amount of food present. Some investigators 

 have found that under such conditions the fungus will increase 

 its production of enzymes. Herissey (1899) and Brunstein (1901) 

 find that the production of emulsin appears to be a starvation 

 phenomenon. The former has found that mycelium, which con- 

 tains no emulsin, can be made to produce it when starved on 



