1923] 



CAMP — CITRIC ACID AS A SOURCE OF CARBON 



287 



the P H through anv considerabl 



tration. 



of hyd 



7, we find the same buffering, but 



there is a marked difference between the curve for 



1 



and that for organism 



There was no rise of acidity 



11 11 • *•«, 



at the start but a gradual falling off followed by a rise to a slight 

 peak and a subsequent falling off. The rise in acidity at this 

 late point might be considered only a variation in certain parti- 

 cular cultures were it not for the fact that several determinations 

 were involved in this "peak." 



For organism 14, solution 2, there was a steady rise in the 



of carbon 



of dextrose ' ' curve, almost from the i 

 r, however, and the increased growth 



This 



seems to be out of proportion to the amount of carbon used 



prod 



How much the buffering rather than the use of the 



Whether 



carbon from the citrate may account for this increase is a question 

 that cannot safely be discussed until more data are available. 

 Generally speaking, organism 14 is the more active and rapid 

 grower when compared with organism 7; likewise it makes more 

 effective use of the citrate radical. Another marked difference 

 between the two organisms lies in the curve of P H in a medium 

 in which dextrose is supplied alone, as noted above, 

 these fungi represent two species is a problem for the m 

 to decide however. 



Sclerotinia Libertiana. — The growth curves for organism 

 found in fig. 19 and the curves for the a 

 Owing to the slow growth of this fungus and the succeeding one 

 (Phomopsis Citri) the culture solution was varied somewhat. 

 Peptone was used as a source of carbon and solution 2 contained 

 M/20 dextrose instead of M/4. Flasks of 100 cc. capacity were 

 used instead of the 300-cc. flasks. 



In the growth curve for solution 1 a sharp peak appears on the 

 ninth day and coincident with it is found a peak in the "loss of 

 carbon" curve and a complete loss of dextrose. On the ninth 

 day it was assumed that there was no dextrose in the solution 



20-21 



but the curve for "loss of carbon" indicates that there was prob- 

 ably considerable sugar present and that the peak on the ninth 

 day indicated erratic cultures. In the normal culture the dextrose 

 would probably be found to disappear about the fourteenth to 



