ELECTROLYTES AND THEIR ACTION 225 



by any other acid, except hydrogen sulphide, a fact which is significant in view 

 of its universal production as the result of oxidations in the organism. 



The effect of rise of temperature on the bicarbonate system is to increase the 

 alkalinity, on account of the greater temperature coefficient of electrolytic 

 dissociation of water than of sodium bicarbonate. 



The hydrogen ion concentration of blood at 38 is 0'4 x 10 ~ 7 and the hydroxyl 

 ion concentration is 7'2 x 10" 7 molar; that is, it is just on the alkaline side of 

 neutrality. This concentration of hydrogen ions reacts alkaline to methyl orange 

 or litmus, acid to phenolphthalein ; the colour of neutral red in such a solution is 

 yellowish orange. 



The method of preparing solutions of known concentrations in hydrogen ions 

 by the use of phosphate mixtures is described in the text. 



The experiments of Ringer on the heart of the frog have shown that, for an 

 efficient artificial saline solution to replace blood, it is not sufficient to take sodium 

 chloride alone in isotonic concentration, but that the presence of potassium and 

 calcium salts is indispensable in addition. In this action, it is the cation that 

 is the necessary part of the salt. 



There is evidence that the salt composition of the blood plasma of higher 

 vertebrates is a relic of the composition of the ocean in pre-Cambrian ages. At 

 this period, the blood plasma had the same salt content as the sea water, and 

 when the ancestors of the present land vertebrates left the ocean at the close 

 of the Cambrian epoch, they carried with them an adaptation to this particular 

 concentration of salts. 



The necessity of salts having "antagonistic" action towards each other's 

 toxic properties applies to protoplasmic action in general. 



A number of examples is given showing the intervention of electrolytes in 

 physiological processes ; enzymes, haemoglobin, hsemolysin, secretion, muscular 

 contraction, pigment cells, coagulation of the blood, transmission of excitation 

 from nerve to muscle and from nerve fibre to nerve cell, action of drugs, 

 phagocytosis, narcosis, the respiratory centre, are referred to briefly. 



The salts of weak acids with weak bases have an importance in that they 

 are much more strongly dissociated electrolytically than either the free acids 

 or the free bases themselves. 



Amphoteric electrolytes, of which proteins and amino-acids, next to water 

 itself, are the most important, are capable of forming salts with either acids 

 or bases, provided that these are fairly strong. There is no adequate evidence 

 of combination with neutral salts. 



There are certain heavy metals which have a very powerful action on living 

 cells, even when in extremely minute concentration. Zinc and manganese greatly 

 favour the normal growth of Aspergillus, while copper, lead, and some other 

 metals have an intensely toxic action on the protoplasm of Spirogyra and animal 

 cells. This latter effect is known as " oligodynamic " action. 



LITERATURE 



Electrolytic Dissociation. 



Arrhenius (1887). Nernst (1911, pp. 353-393). 



Hoeber (1911, pp. 97-181). Raoult (1901). 



Electrode Potentials. 

 Nernst (1889). 



Physiological Action of Electrolytes. 



Ringer (1880-1882). Hoeber (1911, pp. 385-451). 



