CHEMICAL CRITERIA OF ANAEROBIOSIS 13 



an experiment it is always important to add the alkali last to 

 avoid any considerable action of a concentration greater than 

 that indicated by the recorded data. The total volume of liquid 

 in each tube was 10 cc. 



The support with the tubes was then placed in the bath filled 

 with boiling water and the boiling continued for ten minutes, 

 when the support with the tubes was removed and the color or 

 lack of color in the solutions recorded. The reading was repeated 

 five and fifteen minutes after removal from the bath. 



To facilitate the manipulation and observation of so many 

 tubes when an important time element is involved it was neces- 

 sary to divide the experiment in point of time into three sections 

 corresponding to the different quantities of methylene blue used; 

 conditions were duplicated as far as possible in each section with 

 the exception of the quantity of dye, even to the use of dilutions 

 from identical solutions of the three reagents. Also while the 

 data submitted were secured during the space of one afternoon, 

 the tests were repeated several times on other occasions with 

 essentially similar results. 



The lines drawn in table 2 indicate the division at each reading 

 between those tubes showing definite color and those not showing 

 color. Next the line on the colored side there were always tubes 

 partially decolorized. As the tests were exposed to room temper- 

 ature and the air the division line had to be moved in the direction 

 of stronger alkali and stronger glucose, in short, those solutions 

 containing least sugar and least alkali were last to decolorize 

 and first to regain their color. 



Table 2 shows also that larger quantities of glucose and alkali 

 are required for the decolorization of a larger quantity of meth- 

 ylene blue and, further, that a decrease in alkali is compensated 

 for by an increase in glucose. Roughly, within certain limits a 

 five-fold increase in glucose permits halving the alkali and vice 

 versa. It is not difficult to understand the direct correspondence 

 between the amount of dye decolorized and the amounts of 

 glucose and alkali required upon the theory that a definite quan- 

 tity of some substance or substances produced by the action of 

 alkali on glucose and other susceptible carbohydrates is necessary 



