Lewis Knudson 193 



ent solution. Tiie tannic acid in all cases was added after the 

 culture solutions had been steriUzed. The fungus mat was removed 

 and treated as previously described, and for testing its tan- 

 nase content 0.05 gram of the mycehum powder was added to 

 50 cc. of 1 per cent tannic acid solution, containing as an anti- 

 septic 1 per cent toluene. The experiments were all made in dupli- 

 cate and one series of the solutions was incubated for forty-eight 

 hours and the other for eighty hours. 



After the fungus felts had been removed from the culture 

 solution and the liquid filtered, alcohol was added to precipitate 

 any enzjnmes present, the precipitate being collected on filter 

 paper. The filter paper with whatever precipitates accompany- 

 ing were then added to flasks containing the tannic acid solution. 

 After ninety-six hours' incubation these solutions were analyzed 

 for gallic acid. The results obtained are given in table II. 



The results obtained verify the figures of the preceding table. 

 With an increase in concentration of tannic acid there is a corres- 

 ponding increase in the amount of enzyme produced. The excre- 

 tion of enzyme into the culture solutions was evident only in the 

 cultures having a relatively high percentage of tannic acid and at 

 most the excretion was small. 



Influence of concentration of sugar. Since in the preceding exper- 

 iments the amount of tannase produced per unit weight of the fun- 

 gus varies with the concentration of the tannic acid, it seemed 

 desirable to determine the ■effect of maintaining constant the tannic 

 acid concentration while varying the concentration of the cane 

 sugar. In the first experiment duplicate cultures of Aspergillus 

 niger were made in liter flasks containing 300 cc. of solution B 

 -f 2 per cent tannic acid -f- varying amounts of sugar. The myce- 

 hal mats formed were removed, treated as before described and then 

 tested for tannase activity. In measuring the activity of the tan- 

 nase of each culture 100 cc. of a 0.5 per cent tannic acid solution 

 were employed to which was added 1 per cent toluene as an anti- 

 septic. To each flask was added 0.2 gram of the powdered myce- 

 hum. Incubation was given at 34°, and at the end of ninety 

 hours the solutions were analyzed for gallic acid. In table III are 

 given the results of the experiment. The results are the averages 

 of the two tests. 



It is here clearly shown that with increased concentration of 



