104 



Prof. Moore, Dr. Roaf, and Mr. Whitley. [Oct. 9, 



that the concentration of hydrogen ions was greater by one power of ten than 

 in distilled water ; and upon the observations of Loeb himself, (1) that normal 

 sea- water is practically neutral to phenol-phthalein, and (2) that addition of 

 sodium bicarbonate or of di-sodic phosphate, which from their neutral 

 reaction to phenol-phthalein are regarded by Loeb as neutral salts, produced 

 the same favouring effect upon cell-division and reproduction as the caustic 

 alkalies. 



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. 



Such solutions form a peculiar type of their own, which possess the 

 property of behaving either as an acid or as a base. Such solutions can 

 behave in this manner to any substances possessing weak acid or basic 

 properties brought into the same solution, and it is for this reason that such 

 solutions behave entirely differently to distilled water in their associating or 

 dissociating action upon coloured indicators, and so indicate at the same time 

 an acid reaction to one indicator and an alkaline to another. 



A quantity of acid or of alkali can be added to the solution, which would 

 cause an enormous variation in the relative concentration of hydrogen and 

 hydroxyl ions if added to distilled water, without altering to anything like 

 the same extent the relative concentrations of these two ions. 



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 concentrations 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 neutralizes, 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. 



This powerful action of alterations in concentration of hydrogen or hydroxyl 



