ELECTROLYTES AND THEIR ACTION 213 



sea water, in fact, just as quickly as if placed in distilled water. The addition of either 

 potassium chloride or of calcium chloride alone to distilled water or to cane-sugar 

 does not improve it. In solutions containing sodium chloride plus either potassium 

 or calcium chloride, the animals die also as soon as in pure water. Only in a 

 solution containing Na', K' and Ca ' * ions in the proportion and concentration in 

 which they exist in sea water are the animals able to remain alive. It seems clear 

 that the normal semi-permeability of the colloidal constituents of the cell membrane 

 is only kept intact when these three salts are present. Perhaps investigations on 

 the physical properties of proteins and lipoids, as well as of other colloidal systems 

 under the influence of these salts, separately and together, would throw light on 

 the question. 



A similar set of phenomena have been investigated by Loeb and Wasteneys 

 (1911) in the case of the fish, Fundulus, which is not affected by the osmotic 

 pressure of the solutions used in the experiments. In sodium chloride or potassium 

 chloride solutions, of the concentration in which these salts exist in sea water, the 

 fish only lived a few days ; whereas in calcium or magnesium chlorides they lived 

 indefinitely. But, in contrast to what we have seen to be the case in the heart, it 

 was found that salts of sodium and potassium, present together in certain propor- 

 tion, mutually deprived one another of toxic action. In the heart, as will be 

 remembered, the presence of calcium is necessary in addition. A further demand 

 is made by the sea water plant, Ruppia maritima, which requires, according to the 

 investigations of Osterhout (1906), no less than four salts, viz., all the cations 

 present in any quantity in sea water. The following table shows this fact : 



Solution. Duration of life. 



Sea water Indefinite 



Dist. water 80 days 



NaCl 23 



KC1 - 56 



CaCl 9 - - 58 



MgCl 28 - 19 



MgS0 4 - 23 



NaCl + KCl 23 



NaCl + MgCl., - 25 



NaCl + CaCl 2 " 65 



NaCl + MgCI, f KC1 30 



NaCl + MgCl 2 + CaCl 2 - 45 



NaCl + KC1 ^ CaCl 2 - 88 



NaCl + KC1 4- CaCl 2 + MgCl 2 + MgSO 4 - Indefinite 



(Van't HofPs Solution) (more than 150 days) 



Returning to the experiments of Loeb and Wasteneys, direct evidence is 

 given that the effect is of one cation on another, and not of an opposite ion. The 

 fact that above a certain concentration of potassium chloride, no neutralisation 

 of its toxic effect by a sodium salt is possible, suggests a partition of some kind 

 at the cell membrane and most probably an electrical adsorption. We have seen 

 above (page 104) that there is no evidence for the formation of chemical com- 

 pounds of protein with neutral salts, whether they be called " ion-proteids " or by 

 other names. We may also call to mind that one substance may displace another 

 from its state of adsorption, provided that in the process there is a further 

 diminution of free energy of any kind. 



If the proportion of sodium chloride to potassium chloride is much less than that in sea 

 water, for example only eight molecules to one, the toxic action of the potassium is increased. 



It is also interesting to note that calcium chloride itself is not toxic for 

 Fundulus, so that, when it neutralises the toxic action of sodium and potassium 

 chlorides on this fish, it is a case of a non-toxic ion neutralising a toxic one. 

 Calcium has a much more powerful action in neutralising potassium than sodium 

 has, about 500 times as great. Like that of sodium, however, the antagonism is 

 limited and the interesting point about the fact is that the limit is the same, viz., 

 no stronger solution than 6'6 c.c. of 0'5 molar KC1 to 100 c.c. of water can be 



