MUTUAL ANTAGONISM OF INORGANIC SALTS 321 



traces of other salts, magnesium, potassium and calcium chlorides 

 which the water contained. 



Similar phenomena of antagonism have been observed by C. B. 

 Lipman in culture-media containing bacteria. In certain cases, how- 

 ever, no mutual antagonism was observed, as in the case of magnesium 

 and calcium salts acting upon Bacillus subtilis. Furthermore, although 

 the toxicities of potassium chloride and calcium chloride for this, and 

 probably for other am nonifying bacteria, are mutually diminished by 

 their admixture, this is not the case for sodium and calcium chlorides, a 

 mixture of these two salts being more toxic for all proportions of cal- 

 cium than sodium chloride alone. These exceptional phenomena appear 

 to differentiate the ammonifying bacteria very sharply from other types 

 of living tissue. 



The mutually antagonistic toxicity of inorganic salts is therefore a 

 phenomenon which is universally displayed whatever type of proto- 

 plasm we employ. In certain types, as those afforded by the ammoni- 

 fying bacteria, certain antagonisms may fail to be exhibited, but 

 other pairs of salts, again, will clearly annul each other's toxicity. We 

 may infer therefore, that the toxicity of pure salts for protoplasm is a 

 universal property, and that in the majority of instances a mixture 

 of any two salts is less toxic than either of the components alone. It 

 is certainly not an accident that for all the forms of life which have 

 been investigated, the most nearly innocuous mixtures correspond in 

 composition either to sea-water (Van t'Hoff's solution) or to Ringer's 

 solution. In these mixtures of five and three salts respectively the 

 annulment of toxicity is far more complete than in any binary mixture. 

 Sea-water and Ringer's solution are therefore, Physiologically Balanced 

 Solutions, but for certain of the higher animals, for example in the 

 mammals of which the tissues are adapted to an environment having 

 the composition of Ringer's solution, sea-water, as it is composed today, 

 is no longer a physiologically balanced solution. The determination 

 of the physiological balance depends, therefore, upon the properties 

 of the protoplasm upon which the salts are acting and not upon any 

 peculiar properties of the salt-mixture in question, such as double salt- 

 formation, etc. 



THE ORIGIN OF THE MUTUAL ANTAGONISM OF INORGANIC 



SALTS. 



Since the mutual antagonism of salts originates in a property of 

 protoplasm rather than in any physical peculiarity of the salt-mixtures, 

 we are led to infer that the phenomenon must probably be due to 

 chemical interactions between the constituents of the salt-mixture and 

 some constituents of the cells. Now antagonism, as we have seen, 

 may be displayed between almost any pair of metal ions, but it 

 may also be displayed between different pairs of acid radicals. More- 

 over the toxicity of both acids and bases may be partially annulled by 

 21 



