252 



[Vol. 10 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



solution. At the end of 25 days the weights of the mats were 

 determined, and these results are given in table vm. The weights 

 for mats in both the blanks and the solutions to which citric acid 

 was added represent the average of 2 mats. 



TABLE VIII 



GROWTH OF FUNGI WITH FREE CITRIC ACID 



No 



Blank 



2 



3 



4 



5 



7 



11 



Mat 



(mgms.) 



Remarks 



19 



31 



36 

 14 

 22 

 17 



Solution plus citric acid 



Mat 

 (mgms.) 



Remarks 



Solution orange-yellow, 



spores grayish 

 Little growth 



Complete mat formed 



Solution black, some 

 aerial growth 



107 



201 



32 

 27 

 32 

 42 



Growth heavy, spore 



masses greenish 

 Spores green, much white 



aerial mycelium 

 Incomplete mat 

 All growth in solution 



No aerial growth 



The effect of nitrogen source on utilization of citric acid. — In 

 order to test the effect of various nitrogen sources on the utili- 

 zation of citric acid a stock solution was made up as follows: 



citric acid, 157.56 gms.; potassium citrate, 162.17 gms.; dextrose, 

 12.5 gms.; M/1000 FePO«, 4.0 cc; and distilled H,0 to make 1 

 liter. 



Five cc. of the above stock solution diluted 



M/4 of the citrate and dextrose 



th 



This solution had 



H 



of 4 



It 



used as the 



of carbon in the 



the source of nitrogen being varied, KNOi, NELNO,, and 



being used 



It 



found impossible 



Ca(NO,), satis- 



factorily due to the fact that on sterilization calcium citrate 

 precipitated out, or if the nitrate was not added until after sterili- 

 zation, as soon as the fungus grew a little the citrate began to 



due to the change 



The mineral 



were used in 2 concentrations, as originally given and 1/5 of tl 

 concentration. The amount of the solution furnishing the carb 



kept constant throughout 



the amount 



