Lewis Knudson 



167 



The loss in gallic acid indicates that this- substance is used by 

 the organisms as a sourc.e of carbon, which fact agrees with the 

 observations of VanTieghem^' and Pottevin." According to Van- 

 Tieghem, when growth occurs on the surface the tannic acid is uti- 

 lized directly without previous conversion into gallic acid. There 

 is no evidence for this assumption. If the tannic acid is not 

 utilized directly, and it probably is not, then Aspergillus niger is 

 a more vigorous fermentative organism than Penicillium sp. for 

 in the Penicillium culture more tannic acid remained and the 

 decrease in gallic acid was only 39 per cent. The larger gallic acid 

 content of the Penicillium culture is related to the smaller amount 

 of growth and not to the greater practical efficiency as a fermenta- 

 tive organism, and this point is more apparent from later work. 



In table II there are given, separately, data for four of the 

 Penicillium cultures. This table emphasizes a general relation 

 between the amount of growth and the extent of fermentation; 

 furthermore, the disappearance of gallic acid is correlated with 

 increased growth. 



TABLE II. 



Culture No. 1 seems to indicate that the tannic acid transfor- 

 mation is dependent upon the amount of growth, for only a small 

 amount of tannic acid was transformed, but a greater growth 

 during the same period in the other cultures resulted also in almost 

 complete transformation. 



Since the most economical production of gallic acid is dependent 

 upon the amoimt of growth, and growth amount is a function of 

 time, temperature, aeration, and nutrition, then these factors 

 should be important. G/owth is emphasized because with it 



2' Loc. cit. 

 " Loc. cit. 



