528 STUDIES ON RESPIRATION. XV 



toxicity to lanthanum nitrate in that very dilute solutions produce 

 pronounced effects. There is slight increase in the rate in 0.0000125 

 m; the respiration is normal in 0.000015 m, while in higher concentra- 

 tions there is a decrease in the rate. In calculating the molecular 



Rate of COz tH^xioction 

 140%-| 



* 0.0000125 M 



100 / 1 ^ 0.000015 M 



0.001 M 



<^ 0.0025 M 



0.01 M 

 60 min. 



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

 as per cent of the normal) in 0.0000125, 0.000015, 0.001, 0.0025, and 0.01 m Na 

 taurocholate. 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 depend- 

 ing upon the amount of bacterial suspension used, usually 30 seconds. Each 

 curve represents a single typical experiment. 



concentrations of this salt an approximate estimate only could be 

 made because the purity of the salt is doubtful. In making up the 

 solutions 1 gm. of sodium taurocholate in 100 cc. of distilled water was 

 calculated to make about 0.02 m. During the first 10 minutes the 



