Lewis Knudson 175 



the culture solutions. In explanation of the seeming failure of the 

 sugar to protect the gallic acid, the dry weights of felts produced 

 in the corresponding cultures must be compared. The weight of 

 fungus produced in each culture of series II was, at the end of each 

 period, at least three times as great as the weight of the correspond- 

 ing cultures of series I. This increased growth and the accompany- 

 ing increased respiration were sufficient to utilize practically all 

 of the organic nutrients supplied, usually all of the sugar and some 

 of the gallic acid. 



Effect of 10 per cent sugar. Since negative results wereobtained 

 as regards the protection of the gallic acid by 5 per cent sugar. a 

 new series of cultures was made with 10 per cent sugar in solution 

 B to which was added the tannic acid required. On analysis the 

 solution showed after sterilization 4.171 grams of tannic acid and 

 2 . 198 grams of gallic acid per 50 cc. The cultures were incubated 

 at a temperature of 28°, though it dropped occasionallj^ owing to 

 an imperfect thermostat, to 25° and rose likewise to 32°. The 

 cultures were taken down at definite intervals, the weight of the 

 felts determined, and the analyses of the culture solutions made 

 according to the methods previously described. The results follow 

 in table VII. 



The protective action of the sugar is at .once evident. Since the 

 concentration of tannic acid here is double that in the experiments 

 which are included in table III, and therefore a comparison of the 

 yields of gallic acid is not possible, yet the great increase of gallic 

 acid and the maintenance of this increase prove that the sugar has 

 been utihzed in place of the gallic acid. Here it is obviously not 

 true that the greater the weight the less the gallic acid. Cultures 

 Nos. 4, 5, 6 and 7 all vary in weight, yet the amount of gallic acid 

 in each is approximately the same, and any difference may be 

 due to the imperfect method of analysis. Even at the expiration 

 of thirty-five days no decrease of the gallic acid was evident. It 

 may be concluded, therefore, and further experiments prove, that 

 the 10 per cent sugar protects the gallic acid. 



While an increase of gallic acid is maintained in the Penicillium 

 cultures, the increase is relatively small and is due to a slower trans- 

 formation of the tannic acid; practically no transformation of 

 tannic acid occurred until after the fourteenth day. Previous to 

 this time the growth was entirely submersed, but afterwards fructi- 



THE JOURNAL OF BIOLOGICAL CHEMISTRY, VOL. XIT, NO. 3. 



