210 PRINCIPLES OF PHYSIOLOGY 



as the route of the message from the auditory 

 centre to the speech centre has been inter- 

 rupted. If the physician writes the words, 

 " Is not your name John Smith ? " and puts 

 the paper before the patient's eyes, there is 

 the response : " Yes, certainly." Here the 

 message from the visual centre reaches the 

 speech centre, and the patient can utter his 

 name. Frequently also, a patient in certain 

 cerebral diseases may be perfectly conscious of 

 the name of a particular thing that he wants, 

 say a pencil, but he has forgotten the word 

 or uses a wrong one, to his own annoyance, 

 All this may be represented by diagrams, but 

 we must never forget that diagrams only 

 represent men's notions and that the real 

 mechanism may be something very different. 

 The functions of the anterior lobes of the cere- 

 bral hemispheres are unknown. Some have 

 supposed that in them we have the mechanism 

 for volition and the impulses that follow it. 



122. The cerebellum is a regulating mechan- 

 ism. It may have other functions, but it 

 undoubtedly co-ordinates movements. By 

 co-ordination we mean that the time and 



