Lewis Knudson 



i8i 



oxygen varied, as well as to compare the yields under these condi- 

 tions with that obtained when the most favorable conditions were 

 offered, as by the addition of sugar, the following experiment was 

 made: 



Series I. Solution B + tannic acid, flask plugged with cottcto and aero- 

 bic conditions maintained. 



Series II. Solution B + tannic acid + 10 per cent cane sugar, otherwise 

 like the above. 



Series III. Solution B + tannic acid, flasks stoppered with rubber 

 stoppers and contailiing therefore only 75 cc. of air or approximately 15 cc. 

 of oxygen. 



Series IV. Solution B. + tannic acid, flasks stoppered with perforated 

 rubber stoppers, fitted with glass and rubber tubing and clamps. The air 

 was replaced by passing a stream of nitrogen (oxygen-free air) through 

 the flasks for a period of five minutes after inoculation had been made. 



All the inoculations were made with spores of Aspergillus niger, according 

 to the method described by Hasselbring.^i The temperature of incubation 

 varied from 30°-35°. Erlenmeyer fiasks of 125 cc. capacity were employed 

 The results obtained are included in table XI. 



TABLE XI. 



Aspergillus niger. Duration, ten days. 



In comparing the rate of tannic acid transformation under the 

 different conditions it is found that in the order of rapidity of 

 transformation they, are series I to series IV. The yield of gaUic 

 acid was greatest in series II, the addition of cane sugar in this 

 case protecting the gallic acid; somewhat less in series III; still 

 less in series I, where the mycelimn was abundant, despite the 

 fact that it led in th'e amount of tannic acid transformed; and last 

 in series IV. It is noteworthy that the amount of mycelium pro- 



" Loc. cit. 



