238 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Whitley 5 in 1905, when investigating the effects of acid and 

 alkali added to sea-water upon growth and development of 

 Echinus eggs. 



These authors state that " a solution of the mixed 

 phosphates or carbonates in which there is an approximate 

 balance between the concentration of hydrogen- and hydroxyl- 

 ions such that these concentrations are nearly equal, cannot, 

 however, be regarded as neutral in the same sense as distilled 

 water is neutral, or as being acid or alkaline in the same sense 

 as a solution containing only free acid or free alkali can be 

 regarded as being acid or alkaline. 



" Nor will such a solution of phosphates and carbonates, 

 as is present in blood plasma, or sea-water, have a similar 

 action upon living cells to either distilled water or a neutral 

 solution of such salts as sodium chloride of equal osmotic 

 concentration. 



" Therefore blood plasma, and to a less extent sea- water, 

 possess, on account of the mixed phosphates and carbonates 

 which they contain, a steadying action upon variations in the 

 concentration of the hydrogen- and hydroxyl-ions. When acid 

 or alkali is added to the plasma, instead of there occurring a 

 corresponding swing in the concentration of the hydrogen- and 

 hydroxyl-ions, there takes place an alteration in the equilibrium 

 of the ions of the phosphates and carbonates, which neutralises, 

 in great part, the hydrogen- or hydroxyl-ions added, and 

 prevents the plasma becoming markedly acid or alkaline. 

 Without such a controlling action the life of the cells would be 

 rendered impossible, for, as our experiments show, the living cell 

 is most sensitive to even small variations in either hydrogen- 

 or hydroxyl-ion." 



The action of small variations in the hydrogen- or hydroxyl- 

 ionic concentrations of plasma or other " external media " is 

 only to-day gradually becoming recognised in the government 

 of respiratory activity and other fundamental physiological 

 functions, and hence attention may perhaps be drawn to the 



