F. G. GUSTAFSON 39 



2 the rate was higher at the end of an hour in the alkahne solution 

 than in the neutral solution. The decrease in production of CO2 in 

 the alkaline solution is not so great as that shown by the curve, be- 

 cause in taking more than one reading the solution had to be made 

 alkaline again by adding more NaOH, and this produced a buffer 

 action, which increased with every reading. 



It is evident that during the first part of the experiment the produc- 

 tion of CO2 resembles that of the organism in being greater in an 

 acid than in a neutral medium, but less in an alkaline medium than 

 at neutrality. It should be noted that the increase of rate in acid 

 followed by a decrease is also observed in the case of Penicillium. 



The falling off of the rate in the latter part of the experiment 

 might be due to a decrease in the amount of some substance. Evi- 

 dently this is not the sugar; it is doubtful whether it is the hydrogen 

 peroxide, since titration with permanganate as well as the catalase 

 test shows that the hydrogen peroxide has hardly decreased at all 

 by the time the rate has fallen off. It might possibly be an active 

 form of hydrogen peroxide or a catalyzer. It is of course possible 

 that the falling off may be due to the formation of an inhibitory 

 substance. 



According to Spoehr^ there is no reaction between glucose and 

 hydrogen peroxide in a neutral solution, but in a 0.5 m KOH solution 

 2 gm. of glucose had been completely used up at the end of 3 days, 

 forming CO2, formic acid, glycocoUic acid, and a:-hydrox3miethyl-J- 

 arabonic acid. As far as the writer is aware no work has been done 

 with acid solutions. 



It is probable that the reason why Spoehr did not notice any pro- 

 duction of CO2 in the neutral solution was because the amount is 

 very small and the production lasts only a short time, while in the 

 alkaline solutions the production continues for a longer time. 



SUMMARY. 



A neutral solution of dextrose and hydrogen peroxide acts like 

 Penicillium chrysogenum in producing an increased amount of CO2 

 upon the addition of acid, but not upon the addition of alkali. 



« Spoehr, H. A., Am. Chem. /., 1910, xUii, 227. 



