

18 THE PKESENT CONDITION 



that electricity is convertible into magnetism, magne- 

 tism into mechanical force or chemical force, and any 

 one of them with the other, each being measurable in 

 terms of the other, — even so, I say, that great law is 

 applicable to the living world. Consider why is the 

 skeleton of this horse capable of supporting the masses 

 of flesh and the various organs forming the living body, 

 unless it is because of the action of the same forces of 

 cohesion which combines together the particles of mat- 

 ter composing this piece of chalk ? What is there in 

 the muscular contractile power of the animal but the 

 force which is expressible, and which is in a certain 

 sense convertible, into the force of gravity which it 

 overcomes ? Or, if you go to more hidden processes, 

 in what does the process of digestion differ from those 

 processes which are carried on in the laboratory of the 

 chemist! Even if we take the most recondite and 

 most complex operations of animal life — those of the 

 nervous system, these of late years have been shown to 

 be — I do not say identical in any sense with the elec- 

 trical processes — but this has been shown, that they 

 are in some way or other associated with them ; that is 

 to say, that every amount of nervous action is accom- 

 panied by a certain amount of electrical disturbance in 

 the particles of the nerves in which that nervous action 

 is carried on. In this way the nervous action is re- 

 lated to electricity in the same way that heat is re- 

 lated to electricity ; and the same sort of argument 

 which demonstrates the two latter to be related to one 

 another shows that the nervous forces are correlated to 

 electricity ; for the experiments of M. Dubois Rey- 

 mond and others have shown that whenever a nerve 

 is in a state of exciment, sending a message to the 



