450 



M. E. COLLETT 



and Stylonichia, for although their resistance may be identical 

 at one concentration, it is often clearly different at another. 

 The degree of difference in both cases often varies with dilution, 

 as the following figures show. Each figure represents the quoti- 

 ent of the resistance of Euplotes by the resistance of Paramoe- 

 cium or Stylonichia. 



Relative resistance 



Thus we have abundant evidence that each organism reacts in a 

 characteristic fashion to dilution of the reagents . The figures also 

 show that the degree of difference between the organisms is not 

 the same in various acids of the same concentration; that is to 

 say, each organism reacts in a characteristically different way to 

 different acids. 



Nx'o 



H X lo** 



40 50 



Mmu+eS. 10 20 30 40 50 60 iO ^u 



Graph 2, C Relative resistance of Paramoecium, Stylonichia, and Euplotes 

 to equinormal solutions of tartaric (left) and hydrochloric acids (right) at 20°C. 



