PHARMACODYNAMICS OF SALTS AND DRUGS 85 



energy of the system itself into kinetic. The first method of action is 

 clear, but a word may be said as regards the second. Protoplasm, 

 both in its chemical and physical aspects, shows many of the phenom- 

 ena of false equilibrium. It is as if there were considerable differ- 

 ences of potential in the protoplasm itself, but these differences were 

 unable to neutralize or equalize themselves, owing to the presence of 

 certain resistances. It is conceivable that our ions may produce results 

 simply by acting as conductors, or in removing resistances ; acting, in 

 other words, as catalytic agents, without specifying more in detail 

 exactly how these act. As an example of this kind of an action I may 

 mention the generation of the nerve impulse when a motor nerve is 

 suddenly immersed in a salt solution, or when its cut and longitudinal 

 surfaces are connected by a wire. In this case the wire or the elec- 

 trolyte serves by its presence only to equalize the difference in poten- 

 tial between the two surfaces, and the nerve stimulates itself by its 

 own energy. And any electrolyte or any conductor will accomplish 

 this result. To what extent electrolytes may thus affect protoplasmic 

 motions cannot be foretold, but it is certainly possible, and I think on 

 the whole probable, that some of the actions of salts will be found to 

 be of this nature. In such cases the energy content of the salt would 

 be of little importance. But while it cannot be denied that some of 

 the salt action may be of this character, few specific instances are 

 known to me. 



In the second place, salts may appear to act catalytically by means 

 of their valence by bringing about combinations between two sub- 

 stances, this combination resulting in one substance hastening the 

 decomposition of the other. The ferments, for example, may in this 

 way be mordanted, as it were, by some bivalent ions to the substances 

 they ferment, in the manner suggested by Henri. 1 It will, however, 

 be apparent in this case that the power of the ion to form such com- 

 binations of the right degree of looseness from which the ferment can 

 again escape, must be dependent on the chemical affinity of the ion. 

 Since the chemical affinity is very probably a function of the ionic 

 potential, this case also really brings us back to the ionic potential as 

 a highly important factor in the ion's action. 



We may now turn from these hypothetical cases to the other possi- 



1 HENRI, Revue generate des sciences, 1905, i6th year, p. 641. 



