268 COMPARATIVE PHYSIOLOGY OF THE BRAIN 



in the hemispheres ; but the tension of the extensors 

 has decreased, and as a result the tension of the flexors 

 alone determines the position of the arm. 



In Goltz's experiment the centre of the right fore- 

 leg alone had been removed. It has been said that 

 the centre of the left fore-leg situated in the other 

 hemisphere performed the psychic functions for both 

 legs after the operation. I made an experiment to 

 which this objection is not possible. A dog was 

 taught to walk on its hind-legs when it wanted to be 

 fed. Then the hind-leg centres were removed (G, Fig. 

 39) in both hemispheres. In spite of this loss the 

 dog was still able to walk on its hind-legs. When- 

 ever I offered it food or whenever it expected to be 

 fed it rose voluntarily on its hind-feet. The conscious 

 actions or associations for the use of the kind-legs liad 

 not suffered, but there was decidedly a muscular dis- 

 turbance inasmuch as the dog was not able to stand 

 so long on its hind-legs as it could before the opera- 

 tion. I showed this dog at the naturalists' meeting in 

 Berlin in 1886. The day after the demonstration I 

 showed the brain of the animal that had been killed 

 in the meantime. The hind-leg centres had been 

 removed completely. 



It must, however, be explicitly stated that not every 

 limited lesion in the motor centres leads to a disturb- 

 ance. This is not only of importance from a theoretical 

 but also from a practical point of view. A physician 

 need not be surprised if a post-mortem examination 

 shows a circumscribed lesion in the cortex which had 



