Lewis Knudson 



197 



TABLE VII. 

 Aspergillus niger. 



COMPOSITION OP NUTRIENT SOLUTION 



Solution 4 + 25 grains sugar 



Sulotion A + 25 grams sugar + 5 cc. t|- HCl 



Solution A + 25 grams sugar + 5 grams gallic 



acid 



Solution A + 25 grams sugar + 2 grams resorcin . 

 Solution A + 25 grams sugar + 1 grams hydro- 



quinone 



Solution A +25 grams sugar + 5 grams peptone . 

 Solution A + 25 grams sugar tannic acid 



GALLIC ACID 

 INCREAflTC 





 





 











0.489 



From the above table, it is evident that in Aspergillus niger 

 there is a very marked regulatory formation of the enzyme. Pep- 

 tone, which stimulates the secretion of diastase, according to Katz^' 

 has no influence in stimulating the formation of tannase. Gallic 

 acid of the strength used had no effect, which result is surprising 

 in view of the results indicated in table VI and of the further fact 

 that Pottevin^' found the enzyme tannase to be formed in Asper- 

 gillus niger when the organism is cultivated in Raulin's solution 

 with the sugar replaced by gallic acid. Since pyrogallol is a de- 

 composition product of tannic acid, it was thought that perhaps 

 it might stimulate the formation of the enzyme, but the amounts 

 used proved toxic in this particular experiment. Resorcin and 

 hydroquinone were both employed because of their constitutional 

 similarity to pyrogallol, both being dihydroxybenzenes, while the 

 pjTOgallol is a trihydroxybenzene. Negative results, however, 

 were obtained. 



In a similar manner experiments were made in which 10 per cent 

 cane sugar plus various other substances were added to solution A. 

 For the experiment 500 cc. of the solution were used. In deter- 

 mining the presence of tannase, 0.2 gram of the powdered mycehum 

 was added to 75 cc. of a 0.9 per cent tannic acid solution to which 

 had been added 2 per cent toluene as an antiseptic. The results 

 are given in table VIII. 



28 Loc. cit. 



29 H Pottevin: La tannase. Diastase dedoublant 1 acide gallotanique, 

 Compt. rend, de VAcad. des Sci., cxxxi, pp. 1215-17, 1901. 



