180 C. L. BRIGHTMAN, MEACHEM AND ACREE 



4. In a more comprehensive study now in progress, the "salt 

 effect" is under investigation for (a) all degrees of neutralization 

 of several sulfonphthalein indicators and buffer salts from 

 to 100 per cent, and for (b) different concentrations of the indi- 

 cators and buffer salts. 



5. When measuring the limits of tolerance for hydrogen, or 

 other ions, or molecules by organisms, care should be taken to 

 state the concentration of chemicals and buffers used and possi- 

 bly to free the published constants of these "salt effects." 



