336 STUDIES ON RESPIRATION. X 



encing the rate of respiration, an indicator was added to this liquid 

 in the apparatus ; the pH value was observed to remain so nearly con- 

 stant that the change in the rate of respiration could not be attributed 

 to changes in alkalinity of the medium in which the bacteria were 

 placed. 



The control experiments gave the same results as described in a 

 previous paper.^ 



The results are in accord with those of Lipman, except that they 

 show a slight antagonism between magnesium and calcium. The 

 difference between these observations and those of Lipman may be 

 due to the differences in concentration, or in the length of the experi- 

 ments, or to other matters of technique. It is possible that a differ- 

 ence in the strain of bacteria may have something to do with the 

 result. 



In general the results are in accord with those obtained in studies 

 on antagonism in which criteria other than respiration are employed. 



SUMMARY, 



1. Concentrations of MgCL up to 0.01 m have little effect upon the 

 rate or respiration of Bacillus subtilis; at 0.03 m there is an increase 

 in the rate, while in the higher concentrations there is a gradual de- 

 crease. 



2. There is a well marked antagonism between MgCh and NaCl, 

 and a very slight antagonism between MgCh and CaCh. 



