268 ANNALS OF THI 



[Vol. 10 



small amount of dextrose left in the solution. Mat weights for 

 solution 2 showed a normal rise and fall in this respect, attaining 

 a decided maximum and then falling off steadily. 



Sugar had disappeared completely from both solutions on the 

 fifteenth day after inoculation, but if the time is considered as 



when good growth started, then the utilization of 

 sugar in solution 2 was much more rapid than in solution 1. 

 The amount of mat at the point when the sugar completely 

 disappeared from the solution was much greater in solution 2 

 (about 1.5 gm.) than in solution 1 (about 0.62 gm.). This might 

 have been due to the additional citric acid used or to the citric 

 acid combined with a favorable effect upon the utilization of the 

 dextrose. 



The utilization of the citrate radical was remarkably complete 

 in the case of this fungus. The amount of acid by titration had 

 fallen to 2.1 cc. on the sixteenth day after inoculation. Beyond 

 this point the utilization slowed up, but on the twenty-second 

 day there was only about 0.05 gm. of carbon left in the solution, 

 which was less than the amount remaining in solution 1 at the 

 point when the dextrose could no longer be detected. This means 

 that the small quantity of the citrate which was combined with 

 potassium as the cation had disappeared. That the utilization 

 of this combined compound was slower than that of the free acid 

 is illustrated by the falling off in weight of the mat while the 

 combined citrate was still being utilized. This fungus would 

 undoubtedly be classed as a strong user of citric acid. 



Aspergillus sp. — In figs. 4 and 5 are found the curves for Asper- 

 gillus sp. Rapid growth in the 2 solutions began about the same 

 time and the determinations were started on the second day in 



both 



the maximum weight of the mat 



gm. greater than that 



of about two-fifths. This increased maximum weight was attained 

 at about t he time that the dextrose disappeared from the solution. 

 The additional carbohydrate would seem to serve as an auxiliary 

 to the dextrose, but in its absence it was not sufficiently available 

 to keep up the increase of weight, since the w r eight commenced to 

 decrease while the citric acid was still being used. The dextrose, 

 however, was more rapidly used in solution 2 than in solution 1. 



