Mabch 28, 1902.] 



SCIENCE. 



495 



will stimulate slowly in solutions of one 

 gram molecule to 8,000 c.e. ; Na^SO^ in 

 one gram molecule to 25,000 e.c. ; and Na3 

 citrate in solutions of one gram molecule to 

 50,000 c.c. The power of stimulation as 

 indicated by the prolonged tetanic and 

 simple contractions of the muscle extend- 

 ing over hours is also greater than that of 

 the monovalent salts. These observations 

 clearly support the inference that stimula- 

 tion is a function of the anions and also 

 establish the fact that it is a function of 

 the charges the ions bear. They thus sup- 

 port Lo.eb's general idea that valence or 

 the electrical charges of ions determine 

 their physiological action, but demonstrate 

 that it is the negative ions which stimulate. 

 As will presently be shown, however, 

 valence, as such, possibly has no direct 

 influence, but only indirectly determines 

 the action of these ions. 



6. The conclusions just dra^vn led me to 

 infer that the positive ions must prevent 

 stimulation and render the nerve non- 

 irritable. This is shown to be the ease by 

 a comparison of HCl, LiCl, KCl, NH^Cl 

 and NaCl. The last salt stimulates ; in the 

 others the chlorine ion will not stimulate 

 and the nerves lose their irritability. This 

 can only be explained, I believe, by assum- 

 ing that the stimulating action of the 

 chlorine ion is overbalanced by the non- 

 stimulating action of the positive ion, and 

 of these positive ions it appears that H 

 overbalances most, K less, Li still less and 

 NH4 least. If this idea is true it should be 

 possible, by combining'these positive ions 

 with cli- and trivalent more potent anions, 

 to obtain a stimulating compound. This is 

 indeed the case. KCl never stimulates ex- 

 cept by the withdrawal of water; K2SO4 

 will occasionally stimulate the most irri- 

 table nerves in solutions of about the 

 osmotic pressure of the nerve; K3 citrate 

 and Kg ferricyanide will stimulate in solu- 

 tions of a gram molecule to 22,000 c.c. 



of which the osmotic pressure is less than 

 that of the nerve. The same is true for 

 other salts. Lig citrate stimulates in a 

 gram molecule to 30,000 c.c. and (NHt)3 

 citrate in a gram molecule to 40,000 c.c. 

 We thus come to the conclusion that stimu- 

 lation is due to the negative charge of the 

 anions and that the kations prevent stim- 

 ulation. It follows from this that the 

 chemical properties of an acid or a salt are 

 determined by the balance between the 

 anion and the kation. In NaCl the ions are 

 nearly equivalent, but the chlorine slightly 

 overbalances. This idea of the mutual 

 antagonism of the anion and kation may 

 possibly throw light on chemical processes 

 and properties generally. 



7. KMnO^, NaMnO,, and NaClOg will 

 stimulate in solutions of a gram molecule 

 to 12,000 c.c. This stimulation is possibly 

 due to the liberation of some bivalent 

 oxygen anions. 



8. These results are similar to those of 

 Hardy and others on colloidal solutions. 

 Colloidal solutions, the particles of which 

 are positively charged are precipitated by 

 OH ions and anions and the precipitating 

 action of these anions is in proportion to a 

 power of their valence. They seem to be 

 held in solution by hydrogen and possibly 

 other positive ions. As it is well known 

 that protoplasm contains colloids in solu- 

 tion, a fact Hardy has particulai-ly em- 

 phasized, it occurred to me that stimula- 

 tion might be due either to a gelation of 

 the colloids or to their passage into solu- 

 tion. Loeb has frequently mentioned his 

 belief that a variation in the state of the 

 colloids in protoplasm is of impoi'tance in 

 protoplasmic activity and particularly irri- 

 tability. He and others have repeatedly 

 described processes of liquefaction of pro- 

 toplasm, and several years ago he attempted 

 to refer changes in irritability to an altera- 

 tion in the viscosity of protoplasm. I 

 infer that stimulation consists in a 



