CEREBRAL LOCALIZATION 673 



frontal convolution. This conclusion was based in part upon the 

 earlier work of Bouillaud (1825) which tends to show that the speech 

 center is situated in the anterior extremities of the frontal lobes. 



[Furthermore, it was proved by M. Dax and G. Dax (1830) that in 



[right-handed people this area is confined to the left cerebral hemisphere. 

 Lttention has also been called repeatedly to the observation of Galenus 

 that a paralysis of the body results in consequence of lesions to the cere- 

 >ral hemisphere of the opposite side. These data, however, were 

 lot considered of sufficient importance until Broca called special 

 bttention to them. 



In 1864 H. Jackson, stimulated by the work of Broca, proved that 

 bhe muscular spasms characterizing epilepsy, are due to an excitation 

 >f the cerebral cortex. A firm basis was given to this view in 1870 

 )y Fritsch and Hitzig,^ who showed that the cortex of the cerebrum 



|is irritable and that its stimulation evokes perfectly definite muscular 

 responses. These tests were first made upon dogs, but were later on 

 extended to other animals and also to the apes and man by Ferrier, 

 [orsley, Schaffer, Sherrington, Luciani, and others. As a direct 

 result of this work, we find a complete abandonment of the doctrine 



|of Flourens and the acceptance of a view which may be said to be more 

 lirectly in line with the conception of Gall. As has been pointed 



|out above, the latter regarded the cerebrum as a plurality of organs, 

 [n its modified form this doctrine holds that the cerebrum is composed 

 )f circumscribed areas possessing different sensory and motor func- 



|tions. Emphasis is placed upon the fact that these parts are not 

 separated from one another, but are intimately associated and inter- 

 related with one another so as to yield coordinated function. This 

 fundamental conception is in no way altered by the doctrine of Flechsig 



[(1894) which asserts in addition that the different areas of the cerebral 



jeortex consist of projection and association fields. In other words, 



pthe different cerebral spheres seem to be built up of a central core 

 id a peripheral zone which possesses a true psychic character. 

 The Location of the Motor ^rea. — The discovery of Fritsch and Hit- 

 dg, that the cortex of the brain is irritable, completely overthrew the 

 )ld conception of Haller, which assumed that only the underlying 

 rhite matter is pervious to stimuli. The latter view prevailed for so 

 long a time, because it was advocated by such experimenters as Mag- 

 jndie, Longet, Mateucci, Budge and Schiff, and was based chiefly upon 

 iheir inability to evoke motor reactions by the stimulation of any area 

 )f the cerebral surface. As Fritsch and Hitzig made use of the galvanic 



|current, which tends in time to induce electrotonic alterations, their 

 localization left much to be desired. They showed, however, that 

 the muscular effects are confined to the opposite side of the body 

 and may be varied in their intensity by changing the strength of the 



1 Arch, fiir Anat. und Physiol., 1870, 300. 

 43 



