CHAP. IX. MUSO0LAR AND NERVOUS TISSUES. 99 



were employed in the same manner for the pur- 

 pose of ascertaining the effect upon the muscular 

 current. 



Although the effects ohserved may partly arise 

 from an alteration in the contacts of the twa surfaces 

 of the nerve between the electrodes of the galva- 

 nometer, I nevertheless believe, with Du Bois 

 Eeymond, that the passage of an electric current in 

 another portion of the same nerve is capable of 

 affecting the conditions upon which the perve 

 current depends ; but I have not been so fortunate 

 as Du Bois Eeymond in obtaining such decided and 

 definite evidence as could have been wished in regard 

 to the increase of the nerve current.. In all these 

 experiments, the distance of the electrodes, both of 

 the galvanometer and battery, from each other, and 

 the extent of the nerve between each of the elec- 

 trodes, and also the state of the nerve in regard to 

 the dryness of its surface, are points of the utmost 

 importance to be considered and attended to in 

 judging of the final result. 



The only conclusions that can be deduced from 

 the foregoing investigations are the following ; 

 ' ' 1st. That we have no evidence of being able to 

 increase the polarised condition of the nervous and of 

 the muscular tissue by artificial means, such as the 

 electric current ; but it is highly probable, 



2nd, That an increase of this polarized condition 

 may arise from an increased action of those changes 

 which take place in the living animal, such as 



