on Muscidar Action tJimigh the Nerve. 37 



tliey do not increase with their increased strength ; and, Zd, 

 That a difference is obtained with different solutions, the 

 alkaline solutions producing a greater or more constant 

 effect than those of an acid nature. 



The next question which naturally arises for consideration 

 is that respecting the mode of action of chemical reagents 

 upon the nervous tissue, in causing muscular contractions. 

 Do they act by reacting upon the electricity of the nervous 

 tissue, or by reacting upon the compound forming the 

 tissue, and thus indirectly, upon the molecular forces asso- 

 ciated with it ; or in other words, upon nerve-force ? 



We have no reason for supposing that chemical reagents 

 would act upon the nervous tissue in a different manner to 

 that observed during ordinary chemical reactions, much less 

 reason have we for believing that, under these circumstances, 

 the vital property of the tissue, nerve-force, would be in- 

 creased ; we must therefore consider what are the effects 

 that take place during ordinary chemical actions, and I shall 

 limit myself now to the electrical effects. In ordinary 

 chemical actions, it is well known that during chemical 

 combination the compound which performs the part of an 

 acid takes positive electricity, and that of an alkali negative 

 electricity, and the current of electricity which results there- 

 from goes from the alkali to the acid. When we apply our 

 acid and alkaline solutions upon a nerve, the same effects 

 are produced, which can be readily proved by the galvano- 

 meter. Now, the direction of the current, as is well-known, 

 has a most important influence in causing contractions, the 

 direct being far more influential than the inverse. I will 

 first consider the action of a single solution upon a nerve, 

 and believe it to be as follows : — We have first the che- 

 mical changes taking place between the chemical reagent 

 and the nerve, during which changes contractions are excited 

 in the muscle, and an electric current developed at the seat 

 of chemical action ; if an acid be employed, the current 

 goes from the nervous tissue to the acid, if an alkali, from 

 the alkali to the nervous tissue. The strength of the current 

 would depend upon that of the solutions. Now, I do not 

 think that when one solution alone is used, that the mus- 

 cular contractions excited depend upon the electric current 



