1923] 



CAMP — CITRIC ACID AS A SOURCE OF CARBON 



277 



peptone was utilized. This was probably not the case, how 

 and this is further indicated by the difference between the < 



for "loss of carbon 



of dextrose" and the loss of citric acid 



determined by analysis (fig 



TheP 



H 



from 



5.5 at the beginning to 4.1 and back to 6.4 where it remained 

 for most of the course of the experiment. 



Fig. 10. Penicillium digit alum in solution 1. 



It is impossible to draw clean-cut conclusions from the curves 

 in fig. 11. The fact that the loss of citric acid as determined by 



the "loss of carbon 



of dextrose 



would indicate that some product was being formed in the solution 

 from either the citric acid or the dextrose, and, in all probability, 

 from the former. That this substance could not be oxalic acid 

 is obvious from the fact that by the method used oxalic acid 

 would have been included with the citric acid in the barium 

 precipitation. It was not a volatile substance, since it was 

 oxidized in the carbon apparatus and, if an acid at all, it had a 



