228 E. G. SPAULDING. 



true. In any case the osmotic pressure would necessarily be af- 

 fected. Both the stimulating and poisoning effect have further- 

 more been correlated with the valency. 1 In the case of a com- 

 pound of anion and kation, both of which are monovalent, like 

 NaCl which does and KC1 which does not stimulate easily and 

 when in both therefore the charges might seem to offset each 

 other, the stimulating effect, c. g., on the nerve has nevertheless 

 been said to be due to the " overbalancing " of the kation by the 

 anion, and conversely for the inhibitory effect. This of course 

 is not real explanation unless the difference in effect can be cor- 

 related with a difference in some such quality as velocity of dif- 

 fusion or solution tension, and Mathews has this summer shown 

 that the poisoning qualities of the metals and non-metals as 

 well are in fact a function of this latter. Some ground for this 

 " overbalancing" effect seems to be furnished by the fact that in 

 the case in which c. g., a divalent anion is combined with a 

 monovalent kation (2) a greater stimulating effect is observed. 

 Thus KC1 does not stimulate the nerve at its osmotic pressure, 

 K.,SO 4 does occasionally, K 3 citrate stimulates in solutions of a 

 gram molecule to 22,000 c.c. H.,O. But even here the number 

 of opposing charges is the same. The kations therefore differ in 

 some way other than in their mere number of charges. This 

 must also hold true of the anions because of the increasing 

 stimulating effect on the nerve of NaCl, NaBr, Nal and NaFl. 

 The suggestion has been made that the difference in effect when 

 the charges are the same in number is due to a difference in the 

 translatory path of the charge around the atom ; but as a cause 

 for this latter difference must in turn be assigned the admission 

 of an ultimate difference in the atoms themselves would seem to 

 be necessitated. 



While the salts therefore seem to affect the colloidal particles 

 directly, the known inhibitory action of the anaesthetics would 

 accordingly have to be identified with a direct effect on the sol- 

 vent and so only indirectly on the solute. Thus it may be con- 

 sidered that the anaesthetics as being better solvents in most 

 cases than water have the same effect on colloidal particles as do 

 like charges, which repel ; therefore they increase the osmotic 



1 Loeb, Afchiv filr die gesch. Physiologic, Bd. 88. 



