118 V. H. YOUNG 



The results of this experiment show, as does the previous one, 

 that inuhn is much more efficient in stimulating inulase forma- 

 tion than any of the other substances used. Soluble starch 

 stands next in order of efficiency, being approximately 65% as 

 efficient as is inulin. Sucrose is much less efficient than starch, 

 while glucose is the least efficient of the four substances tested. 



The two experiments just described give tolerably conclusive 

 results regarding the effects of the carbohydrates used on inulase 

 secretion, but in order to check these results still further the 

 experiment was repeated in all of its essential details, with cer- 

 tain minor variations in the methods employed. While all or- 

 dinary precautions were observed to prevent bacterial action in 

 experiments on the hydrolysis of inulin by inulase, it seemed 

 probable that in the course of a day or more, even though tolu- 

 ene was used, some bacterial action on the inulin might have 

 taken place. For this reason a third experiment along this line 

 was run for a period of only four hours. With the precautions 

 taken with regard to the sterilization of all glassware, water, 

 etc. it seems highly improbable that even the slightest amount 

 of hydrolysis could have been brought about by bacteria. 



As a further check on the accuracy of the above experiment, 

 the sugar analyses were made by Fehling's gravimetric method 

 rather than by the volumetric method previously employed. 

 Since the period of hydrolysis of the zymolyte was rather short, 

 the percentage of hydrolysis was naturally much smaller than 

 before, but this should not alter the comparative relations of the 

 experiment. Besides being grown on inulin, soluble starch, su- 

 crose and glucose, Aspergillus was also grown on maltose and as in 

 the previous experiments these substances were employed in the 

 concentration of 1%. 



The results of the experiment described in the last paragraph 

 above are strikingly in accord with the results tabulated in 

 table 3. Cultures on inulin show a much greater amount of 

 inulase than do any of the other cultures. As in the previous 

 case starch stood next in efficiency, sucrose and maltose were 

 next in order, while glucose was far less efficient than any of the 

 other carbohydrates employed, as shown before. The numerical 



