222 ON THOUGHT IN MEDICINE. 



enthusiasm for work in the right direction that is, 

 Johannes Miiller, the physiologist. In his theoretical 

 views he favoured the vitalistic hypothesis, but in the 

 most essential points he was a natural philosopher, firm 

 and immovable; for him, all theories were but hy- 

 potheses, which had to be tested by facts, and about 

 which facts could alone decide. Even the views upon 

 those points which most easily crystallise into dogmas, 

 on the mode of activity of the vital force and the activity 

 of the conscious soul, he tried continually to define more 

 precisely, to prove or to refute by means of facts. 



And, although the art of anatomical investigation was 

 most familiar to him, and he therefore recurred most 

 willingly to this, yet he worked himself into the chemical 

 and physical methods which were more foreign to him. 

 He furnished the proof that fibrine is dissolved in blood ; 

 he experimented on the propagation of sound in such 

 mechanisms as are found in the drum of the ear; 

 he treated the action of the eye as an optician. His 

 most important performance for the physiology of the 

 nervous system, as well as for the theory of cognition, 

 was the actual definite establishment of the doctrine of 

 the specific energies of the nerves. In reference to the 

 separation of the nerves of motor and sensible energy, 

 he showed how to make the experimental proof of 

 Bell's law of the roots of the spinal cord so as to 

 be free from errors; and in regard to the sensible 



