Lewis Knudson 



195 



The results confirm the evidence of the preceding experiment, 

 though the differences due to sugar concentration are not so marked. 

 This may have been due to the longer period of incubation. 



V. INFLUENCE OP NUTRITION. 



Since Dox has found in Penicillium camemberti that the various 

 enzymes are produced irrespective of the nutrition of the fungus, 

 an experiment was made to determine definitely if the enzyme 

 tannase could be produced in two Penicillium species when tannic 

 acid is withheld from the culture solution. Penicillium sp., 

 which I have previously described,^^ and Penicillium rugulosum 

 were employed in the experiment. They were cultivated in 100 

 cc. of a nutrient solution which was composed on the one hand of 

 solution B + 5 per cent sugar and, on the other, solution B + 5 

 per cent sugar + 2 per cent tannic acid. The mycelial felts, as 

 before, were removed just before spore formation, treated as pre- 

 viously described and pulverized. For determining the presence 

 of the enzyme tannase 100 cc. of a 1 per cent tannic acid solution 

 were used to which was added 2 per cent toluene as an antiseptic 

 and 0.1 gram of the pulverized mycelium. The solutions were 

 incubated for twenty-eight days at a temperature of 33°. They 

 were then analyzed for increase in gallic acid. All cultures and 

 determinations were made in triplicate. As is evident from the 

 table tannase was formed only in the presence of tannic acid. 



TABLE V. 



OBGANI^M 



Penicillium sp 



Penicillium rugulosum. 

 Penicillium sp 



Penicillium rugulosum. 

 Check 



COMPOSITION OP SOLUTION 



GALLIC ACID 

 PRESENT 



Solution B + 5 per cent sugar 

 Solution B + 5 per cent sugar 

 Solution B + 5 per cent sugar 



+ 2 per cent tannic acid 

 Solution B + 5 per cent sugar 



+ 2 per cent tannic acid 



0,287 

 0.287 



0.822 



0.822 

 0.287 





 



0.535 



0.535 

 



Experiments were next made to determine the influence of 

 replacing the sugar by other compounds and of adding to the 

 nutrient solution various reagents. For this experiment solution 



26 Loc. cit. 



