EFFECT ON ORGANIC FUNCTIONS 23 



the sour taste of acid salts is stronger than would be 

 expected from the concentration of H ions, but he 

 does not consider that this militates against an 

 explanation of taste from the ionic standpoint. If 

 the taste is due to a chemical action upon a substance 

 on the surface of the tongue, the sensation may be 

 accompanied by the removal of H ions, and further 

 dissociation would then occur in accordance with 

 mass-action law. Although the degree of dissociation 

 in a liquid is correctly ascertained no quantitative 

 connexion could be obtained from the taste. This 

 explanation is also in agreement with paralysis of 

 the sense of taste which follows the application of 

 concentrated solutions to the tongue. H- and OH 7 

 ions are those which possess the most marked taste, 

 and are those most likely to cause reactions in the 

 substance of the tongue, and such phenomena are 

 not opposed to an explanation of taste by the ionic 

 theory. 



The effects of dissociated substances upon many 

 organisms have been observed. Acid ions, even 

 C0 2 , stop the contractile manifestations of proto- 

 plasm ; the ions of alkalies at first increase its 

 activity. W. E. Garrey* states that the effect of 

 such chemicals upon flagellated infusoria is analogous 

 to that of heat, light, galvanism, and other stimuli. 

 Inorganic acids have equal effects upon them, if 

 their ionic concentration is the same ; but organic 

 acids behave differently and their effect is greater 

 than would be expected. When fungi are subjected 

 to the action of deleterious ions they offer in general 

 more resistance than higher organisms. Clarke f 



* Amer. Jour. Physiol, 1900, iii., 291-315. 

 t Jour. Physiol. Chem., 1899, iii., 263. 



