124 V. H. YOUNG 



chemical formula, although better established than that of 

 starch, has not been placed on a firm basis. Neither have the 

 analytical methods for the determination of inulin or of fructose 

 in the presence of inulin been placed on an entirely satisfactory 

 basis. However, analytical methods have proved to be suf- 

 ficiently accurate to allow comparative studies, which have given 

 reasonably uniform results. Inulin is much more soluble than 

 starch and can be employed in fairly concentrated solutions with 

 the assurance that solutions are of uniform strength. Again, the 

 similarity between the structure of inulin and that of starch 

 makes a comparison of their corresponding enzymes of real 

 value. In addition to these considerations, inulase has been 

 little studied from the point of view of its regulatory secretion, 

 and the existing data of this nature seem highly contradictory 

 in character. 



Dox (1910) and Boselli (1911) have arrived at very different 

 conclusions in regard to the quantitative regulation of inulase 

 by fungi, as noted in the review of the literature; and in select- 

 ing the method of attacking the problem it seems best, there- 

 fore, to compare their methods and results with a view to deter- 

 mining whose results are more likely to be correct. The main 

 factors in experiments of this nature are the methods of growing 

 the fungus and the methods of securing and employing the 

 enzymes produced. There appears to be no essential difference 

 in the methods of growing the fungus, but in the methods of us- 

 ing the enzyme produced, one finds that there is much difference. 

 Dox has employed the mycelium only, treating it at the begin- 

 ning of the sporulating period according to the well known 

 ''acetone daurhefe" method. Boselli, on the other hand, has 

 attempted to study the combined activities of the enzymes of 

 the culture medium and the enzymes as extracted directly from the 

 mycelium. Theoretically this appears to be the ideal method 

 of experimentation, accounting as it does for all of the enzyme 

 that has been produced and also employing the enzyme directly 

 without precipitation, which has been repeatedly shown to lower 

 the activity of the enzyme. Practically, however, this latter 

 method does not lend itself to quantitative methods of study, 



