MATILDA M. BROOKS 



13 



of these two salts (in the concentrations used) that produces normal 

 respiration. It is of interest to note that Osterhout^ and Lipman^ 

 also obtained two maxima with these salts in experiments upon wheat 



Rate of COj^ production 



Fig. 5. Curves showing antagonism in the effect of salts on the respiration of 

 Bacillus suhtilis. Curve A, antagonism between NaCl, 0.8 m (left), and CaClo, 

 0.8 M (right) ; Curve B, antagonism between NaCl, 1 m (left), and KCl 1 M (right) ; 

 Curve C, antagonism between KCl, 1 M (left), and CaCl2, 1 m (right). The or- 

 dinates represent rate of respiration (expressed as per cent of the normal); the 

 abscissae represent molecular proportions of the salts used. Thus, in Curve A, 

 the ordinate at the extreme left represents the rate in NaCl 0.8 m, while the ordi- 

 nate at the extreme right represents the rate in CaCl2 0.8 m. The ordinate in 

 the middle represents the rate in 50 parts NaCl 0.8 m + 50 parts CaCl2 0.8 m. 

 The normal rate (which is taken as 100 per cent) represents a change in pHfrom 

 7.78 to 7.60 in about 30 seconds, varying according to the number of bacteria 

 used. Curve A, average of two experiments; Curve B, average of five experi- 

 ments; Curve C, average of three experiments. Probable error less than 3 per 

 cent of the mean. 



« Osterhout, W. J. V., Bot. Gaz., 1909, xlviii, 98. 



