672 THE CEREBRUM 



that, therefore, the cerebral cortex is divisible into several, minor or- 

 gans, has been made use of by Gall, ^ a physician of Vienna, in framing 

 his system of cranioscopy, or, as it was called later on by Spurzheim, 

 the science of phrenology. Being of the firm belief that the psychical 

 power of an individual is seated in the cerebrum, he outlined definite 

 areas upon the external surface of the cortex in accordance with defi- 

 nite mental qualities. This localization he based upon a study of the . 

 external characteristics of the cranium of people who showed especially 

 well-marked mental faculties. He reasoned that the cerebral area 

 controlling a certain function must increase in volume in proportion to 

 the state of development of the latter; moreover, this internal change 

 must betray itself in a greater prominence of the skull plate of this 

 particular area. While this deduction is in general correct, Gall 

 carried it too far, and was in no position to furnish experimental 

 proof for his assertions. These facts were subsequently exploited 

 for commercial purposes and no definite scientific good was derived 

 from them, at least, not immediately. 



This assumption of Gall that the cerebrum is not a single organ or 

 functional unit, was first criticised by riourens,^ and his followers 

 Magendie, Longet, Budge and Schiff. It was finally pointed out that 

 the mental life of man cannot be subdivided into a series of independent 

 faculties, this conclusion being based upon the theoretical and experi- 

 mental data of different writers. Thus, Flourens showed that the 

 destruction of the cerebrum of pigeons is followed by a loss of intelli- 

 gence which it is impossible to grade by a partial destruction of this 

 organ. In other words, the successive removal of certain parts of the 

 cerebrum did not give rise to a progressive series of psychic defects, 

 but to a uniform lowering of the sum total of the psychic processes. 

 This inability to localize certain functions in definite areas of the 

 cortex led him to believe that the cerebral hemispheres act as a uni- 

 form whole and produce the phenomena of consciousness jointly. 

 This conclusion found substantiation in the symptoms displayed by 

 individuals who had suffered accidental injuries of the brain. It will 

 be shown later on that this conception of Flourens is correct only in 

 part, because subsequent researches have proved beyond doubt that 

 there is a distinct difference in the functions of the different parts of 

 the cerebrum, or rather in the quality of the contribution which they 

 severally make to consciousness. Mourens, however, was correct in 

 his belief that the psychic life is really dependent upon a proper 

 functional interaction of the different constituents of the brain. 



This doctrine of Flourens was commonly accepted until Broca 

 (1861) gave final proof of the fact that the loss of speech so frequently 

 associated with apoplexy, is due to the destruction of the left inferior 



1 Recherches sur la syst. nerv. en general et sur celui du cerveau en particulier, 

 1810. 



2 Rechersches experimentales sur les proprietes et les fonctions du syst. nerv. 

 dans les animaux vertebres, 1824. 



