492 



PHYSIOLOGY 



intelligence and associative memory with the actions founded on such 

 endowments, removal of portions of the brain caused simply a lowering 

 of these functions, and it was a matter of indifference whether the 

 brain substance was taken from the anterior or from the posterior 

 portions of the hemispheres. Flourens therefore concluded that the 

 cerebral hemispheres acted as a whole as the seat of the will and intelli- 

 gence. There is no doubt that Flourens was so far perfectly correct, 

 since all parts of the brain must co-operate in determining the psychical 



condition of any individual 

 ASG 



Scr 



COR 



in any given moment. He 

 was, however, as later re- 

 searches showed, in error in 

 thinking that no difference 

 could be distinguished 

 between the parts contri- 

 buted by the various con- 

 volutions of the brain to 

 the organic whole which is 

 called consciousness. 



As we have seen, histo- 

 logical evidence, which in 

 the case of the cerebellum 

 displays a marked uni- 

 formity throughout the 

 whole cortex, in the case of 

 the cerebrum reveals strik- 

 ing differences between its 

 various areas. The demar- 

 cation of the cerebral cortex 

 into areas according to the 

 histological structure of 



their grey matter agrees with, and in many cases supplements, the 

 results procured by an experimental inquiry into the functions of 

 the different parts. 



That there is a localisation of function in the cortex so far as con- 

 cerns the movements of the two sides of the body was known to 

 Galen, who mentions the occurrence of paralysis on one side of the body 

 as a result of lesions in the brain of the opposite side. In 1861 a 

 French physician, Broca, confirming older statements by Dax and 

 Bouillaud, pointed out that aphasia, i.e. loss of power of speech, when 

 it occurred in right-handed people was always associated with a lesion 

 of the third frontal convolution of the left hemisphere, which has ever 

 since that time been known as Broca's convolution. Hughlings 

 Jackson in 1864 drew attention to the connection of localised spasms 



FIG. 223. Upper surface of dog's brain, showing 

 results of excitation. (FRITSCH and HITZIG. ) 

 A, neck muscles ; +, movements of fore 

 limb ; **, movements of hind limb ; O, move- 

 ments of face ; ASG, anterior sigmoid gyrus ; 

 PSG, posterior sigmoid gyrus ; COR, coronary 

 fissures ; Scr, crucial sulcus. 



