MATILDA M. BROOKS 



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represent molecular proportions. The ordinate in the center repre- 

 sents the rate of respiration in a mixture of 50 cc. of each component; 

 the ordinate at the extreme left represents the rate in a pure solution 

 of one component; the ordinate at the extreme right, the rate in a 



Rate of CO2 production 

 120%7j 



100 



Concentration 



0.8 M 



Fig. 2. Curve showing the rate of respiration of Bacillus subtilis (expressed 

 as per cent of the normal) as affected by La(N03)3. The normal rate 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. Average of three 

 or four experiments; probable error of the mean less than 2 per cent of the mean. 



Table I accompanies Fig. 2, showing the results at concentrations too small to 

 be represented properly in the figure. 



