MYSTERIES OF LIFE AND MIND 



approaches a state of jelly. This would be brought 

 about by precipitation of the colloid particles. 

 And if the latter are positively charged, as Hardy 

 has shown, then it would be a "negative current 

 which would offset such a precipitation, and hence 

 a negative current that produces a stimulus of a 

 nerve. 



It was precisely this that Professor Mathews 

 found to be true, that the stimulus of a nerve by 

 an electric current always proceeds from the nega- 

 tive pole, the cathode. Here seemed quite strik- 

 ing proof that his theory was well grounded. It 

 seemed the opening towards a complete explana- 

 tion of nerve action. Slight wonder if a young 

 man of thirty, keen to enter the front of the lists, 

 should sit up nights thinking about it, and Pro- 

 fessor Mathews did. 



Taking the muscles of a frog, to which the motor 

 nerve was still attached by one end, he undertook 

 the systematic study of various solutions of salts, 

 such as Professor Loeb had used to make the muscles 

 beat directly without the intervention of the nerves. 

 The muscle itself was hung so that when it con- 

 tracted it made a lever work up and down, and 

 the latter, with a pencil attached, would trace the 

 jerks on a revolving drum. The nerve was bathed 

 in the solution. To see the thing in action with 

 one's own eyes gives one an uncanny feeling. 



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