8 



STUDIES ON RESPIRATION. VHI 



0.1, 0.5, 0.8, and 1.0 m. During the first 10 minutes the bacteria 

 are under normal conditions and the curve (broken line) is horizontal. 

 After this (at the point marked on the abscissa) the salt is added. 



Raite of CO^ production 



1507,^ 



100 -. 



50 



oo.i5n 



• 0.1M 



30 



-oQsn 



o.sn 



l.OM 



60 mm. 



Fig. 1. Curves showing the rate of respiration of Bacillus subtilis (expressed as 

 per cent of the normal) in 0.15, 0.1, 0.5, 0.8, and 1.0 m NaCl. The zero point 

 on the abscissa denotes the beginning of exposure to the salt solution; previous to 

 this the bacteria were in 0.75 per cent solution of dextrose in distilled water. The 

 normal rate (which is taken as 100 per cent) represents a change in pH value 

 from 7.78 to 7.60 in a number of seconds depending upon the amount of bacterial 

 suspension used, usually 30 seconds. Each curve represents a single typical 

 experiment. 



For example, the addition of sufficient NaCl to make the concentra- 

 tion 0.15 M produces a rise in the rate, which remains constant during 

 the period of experimentation. When the concentration of NaCl 



