302 



L. H. HYMAN. 



TABLE IV. 



ACTION OF HYDROCHLORIC AND SULPHURIC ACIDS AT DIFFERENT HYDROGEN 

 ION CONCENTRATIONS ON THE OXYGEN CONSUMPTION OF Planaria. 



All figures represent cc. of oxygen consumed per hour at 20 C. Each vertical 

 column constitutes one experiment, giving successive determinations on the same 

 lot of worms. 



Normal Respiration, pH 8.0. 



.42 



44 



37 



.48 



34 



34 



.42 .43 



38 



.40 



50 



58 



43 



Respiration in Acidified Water. 



Per cent. Initial Depression. 



33 



40 



46 J 



16 



35 



34 



37 



45 



100 

 90 

 80 

 70 

 60 



Recovery after Return to Normal Water. 



B 



8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 



FIG. i. Graph of the action of acids on the rate of oxygen consumption. 

 Curve A, action of hydrochloric acid in carbonate-free water. Curve B, action 

 of hydrochloric acid in ordinary water. Dashed line, average curve of the de- 

 pressing action, obtained by averaging all of the acids except butyric. Percentage 

 of depression, normal respiration being taken as 100, on the ordinate, pH on 

 the abscissa. 



