130 V. H. YOUNG 



pure water. In view of the fact that the presence of the zymolyte 

 has been shown to result in an increased enzyme production, it 

 seems probable that enzyme production is a direct result of 

 chemical stimuli and it is difficult to understand how the ab- 

 sence of stimulatory agents can have the same effect as their 

 presence. 



Other investigators have apparently considered the presence of 

 substances, which are acted upon by digestive enzymes only with 

 difficulty, as being a starvation phenomenori. Thus the increased 

 production of diastase under conditions, when only starch is 

 present as the source of carbon has been considered by such in- 

 vestigators as a hunger phenomenon, since they also find that 

 diastase production is more or less inhibited if such substances as 

 sucrose or glucose be present in addition to starch. Clearly this 

 condition is very different from the condition of starvation first 

 mentioned: i.e., the entire absence of food substances. It is en- 

 tirely unnecessary to consider enzyme formation in this second 

 case as a hunger phenomenon since evidently the contact of the 

 zymolyte with the organism is the stimulatory agent which af- 

 fects enzyme production. 



The results of the present study on the regulatory formation of 

 inulase would indicate that stimulation to increased production 

 depends upon a direct chemical stimulus due to substances present 

 in the culture medium. Inulin is the most efficient of the sub- 

 stances used in stimulating inulase production. An increase in 

 the amount of inulin present causes an increase of inulase pro- 

 duction rather than a decrease, and very small amounts of inu- 

 lin are unable to increase inulase production. The results also 

 show that the stimulatory effects of inulin are independent of 

 the presence of glucose, which supposedly is a more easily assimi- 

 lated substance than inulin. The results shown in tables 7 and 

 8 indicate that, if inulin is present in sufficient amounts to stimu- 

 late inulase production, the presence of glucose in equal amounts 

 has no influence on inulase production. If the stimulatory ef- 

 fect of inulin is due to some relation of the dissolved particles to 

 the plasma membrane of the organism or to some similar stimu- 

 lation, then glucose would not be expected to have an inhibitory 



