196 Mr, H. F. Baxter on. the Force evolved 



connected by means of the lumbar nerves and a portion of the 

 vertebral column, were each placed in separate vessels containing 

 the solution of common salt ; the muscles of one limb were then 

 made to contract, and an immediate effect upon the needle was 

 observed, the contracted limb being positive to the other from 

 3° to 4°. To prevent the fluid from being scattered upon the 

 electrode, a piece of glass was attached to the part as a weight 

 to avoid too great motion of the limb. In some instances both 

 feet were removed: the effect upon the needle was still the same. 



Similar results were obtained with the acid solution, but with 

 the alkaline solution the effects varied, especially so if the solu- 

 tion were strong. The alkali acted apparently upon the mucous 

 secretion of the skin. 



Great care was required to have the cutaneous surfaces clean 

 previous to the introduction of the limbs into the solutions, so 

 that no current could arise therefrom. 



Is it necessary to place the nerve of a galvanoscopic frog in con- 

 tact with the longitudinal and transverse section of a muscle in 

 order to obtain the necessary contractions ? Repeating the expe- 

 riments of Matteucci*, we found that the contraction might be 

 obtained without placing the nerve in contact with the muscle. 

 At the same time we must add, that the effect upon the galva- 

 noscopic frog appeared greater when its nerve was placed trans- 

 verse to the muscular fibres than in any other position. 



The results of our experiments tend to establish the following 

 conclusions, viz. — 



First. That during muscular contraction in man and in frogs, 

 an effect upon the galvanometer may be obtained indicating the 

 manifestation of an electric current. 



Secondly. That this manifestation of an electric current is due, 

 in a great measure, to secondary reactions, viz. between the 

 animal secretions and the solutions on the one hand, and between 

 the solutions and the platinum electrodes on the other ; but that 

 there nevertheless remains a residual effect which we cannot refer 

 to either of these actions, or to those pointed out by Du Bois- 

 Reymond. 



Concluding Remarks. 



The numerous instances in which an electric current may be 

 shown to exist, naturally renders any conclusion deduced from 

 results obtained by means of the galvanometer extremely doubt- 

 ful. If these remarks are applicable to physical researches, where 



* Phil. Trans. 1850. Ninth Series. 



