INULASE FORMATION IN ASPERGILLUS 87 



allowed to stand during the time of the experiment and tested 

 for reducing sugar. To determine if possible whether or not 

 zymase from the mycelium might possibly break down some of 

 the reducing sugar formed, fermentation tubes containing inulin 

 and the enzyme extract were set up to detect the possible evolu- 

 tion of C02. These checks in all cases gave negative results and 

 for this reason all of them except the first form were abandoned. 

 It was, however, found that inulin solutions of a strength equal 

 to that of the experiments possessed a low-reducing power, after 

 standing for the time of the experiment, and this amount was 

 subtracted from all results. After being incubated for the re- 

 quired time, the flasks were heated to the boiling point to arrest 

 enzyme action, cooled to room temperature and again made up 

 to 250 cc. 



The activity of the inulase tested was judged by the amount 

 of reducing sugar present at the end of the incubation period. 

 This was determined by use of Fehling's volumetric method 

 (Haas and Hill, p. 75), and later a similar experiment was con- 

 ducted using the Fehling gravimetric method (Haas and Hill, 

 p. 85). The volumetric method of analysis offers some difficul- 

 ties, when carried out in the presence of inulin, due to a slight 

 hydrolysis of the inulin if boiling with the alkaline Fehling's so- 

 lution is continued for any considerable time. For all practical 

 purposes, this difficulty is avoided if the solution to be analyzed is 

 added rapidly nearly up to the end-point. By rapid manipula- 

 tion an end-point which checks within a fraction of a percentage 

 may be obtained. 



It was, however, thought best to repeat the experiments by 

 the gravimetric method in order to have a check on the work. 

 This method gave results which check rather closely and from 

 their general similarity to the results obtained by the volumetric 

 method there seems to be little reason for believing that the 

 results obtained are not reliable. All analyses, both volumetric 

 and gravimetric, were run in duplicate and the results computed 

 according to factors given by Haas and Hill. 



