VITAMINS 



183 



10 14 



Days of incubation 

 Fig. 40. Effect of concentration of thiamine on the rate and amount of growth of 

 Sordaria fiynicola in 25 ml. Hquid glucose-casein hydrolysate medium, initial pH 3.8. 

 Compare with Fig. 38. (After Lilly and Barnett, Am. Jour. Botany 34: 134, 1947.) 



40 



30 



T5 



O20 



10 



0.05 0.1 0.2 0.3 0.4 



Microgroms p-aminobenzoic ocid per 25 ml. medium 



0.5 



Fig. 41. Effect of concentration of p-aminobenzoic acid at different pH values on the 

 growth of a mutant of N eurosj}ora crassa deficient for this vitamin. The fungus was 

 grown on liquid glucose-casein hydrolysate medium for 3 days. (Drawn from the 

 data of Wyss, Lilly, and Leonian, Science 99: 18, 1944.) 



