174 



The Philippine Journal of Science 



1916 



The figures in Table VII demonstrate that B. pestis in the veal- 

 infusion broths tolerates acid up to about 4 per cent (3.8 to 4.2), 

 which is 1 to 1.5 per cent higher than in beef-extract media. 



THE INFLUENCE OF TEMPERATURE AND OXYGEN PRESSURE ON RATE OP 



FERMENTATION 



It is a recognized fact that the temperature at which B. pestis 

 is cultivated influences the organism to a considerable degree. 

 In consideration of this the rates of acid production at incubator 

 and room temperatures were compared. In Table VIII are 

 shown the end reactions in 1 per cent Hiss's serum waters 

 containing levulose, maltose, salicin, arabinose, galactose, and 

 glycerin. The room temperature ranged from 27 to 30° C. 

 during the period of cultivation. 



Table VIII. — Comparison of fermentation of 1 per cent sugar serum,-waters 

 at incubator and room temperatures. 



[End result after ten days ; symbols as in Table I ; the day of observation in parentheses.] 



Strain. 



A 

 B 

 C 

 D 

 E 

 F 

 G 

 H 

 I. 

 J 



Levulose. 



37°. 28°. 



4+ (4) 4+ (3) 

 4+ (3)4+ (3) 

 4+ (3)4+ (3) 

 4+ (3)4+ (3) 



3+ (7) 



4+ (4) 



+ (3) 



4+ (3) 



2+ (5) 



+ (8) 



4+ (3) 



4+ (3) 



4+ (4) 



4+ (3) 



4+ (3) 



4+ (3) 



Maltose. 



37°. 28°, 



(4)4+ 

 (4)4+ 

 (8)4+ 

 (3)|4+ 

 (4)4+ 

 (6)4+ 



Salicin. 



37°. 28°. 



+ (10) 

 ± (4) 



± (4) 



1 (9) 



± (10) 



(4) 

 (6) 

 (9) 

 (9) 

 (6) 

 (7) 



(4) 

 (8) 



Arabinose. 



37°. 28°, 



4+ 



2+ 



2+ 



4+ 



+ 



+ 



2+ 



4 + 



+ 



(3) 

 (4) 

 (9) 

 (3) 



Galactose. 



37°. 28°, 



(5) + 



(5) 



(6) 



(4) + 



(5) + 

 (3) + 



(3)4+ (4) 



(2)4+ (10) 



(2)2+ (9) 



(2)4+ (5) 



(3)2+ (5) 



(2)1 + (3) 



(5) 2+ (9) 

 (3) 



(2) 



(3) 

 (3) 



(3)4+ (4) 



Glycerin. 



37°. 28°, 



+ (4) 



+ (8) 

 + (5) 



The serum-water cultures represented in Table VIII evidenced 

 a considerably greater activity at the room temperature, at which 

 saprophytism is pronounced, than at 37° C, the temperature of 

 human-body parasitism. 



Similar, though somewhat less marked, is the difference in 

 effect of these temperatures with litmus agars. In practically 

 every instance acidification began more quickly on the room- 

 temperature slants and in most instances became complete 

 sooner. Further, in several cases it became complete only at 

 room temperature. With 0.5 per cent agars several maltose 

 cultures in the incubator became partially acid and reverted to 

 neutral, while the corresponding room-temperature cultures be- 

 came and remained strongly acid. 



