THE FUNCTIONS OF THE CEREBRAL CORTEX 281 



defined localization of these or any other mental functions, in 

 the sense that a specific cortical area is the exclusive organ of a 

 particular mental element. 



As a reaction against the crude theories of Gall and Spurzheim 

 it was commonly believed up to the year 1870 that there is no 

 definite localization of functions in the cerebral cortex, but that 

 the cortex functions as a whole, much like the cerebellar cortex, 

 with no clearly defined functional areas. This view and modi- 

 fications of it are still very prevalent. Goltz, who succeeded 

 in removing all of both cerebral hemispheres from several dogs, 

 holds that different psychic functions are not localizable in the 

 cortex, but that removal of cortical areas simply diminishes 

 general intelligence in proportion to the amount of cortex re- 

 moved. Even total removal of the cortex, in his opinion, does 

 not completely destroy consciousness. Many physiologists 

 have, on the other hand, taught that particular conscious func- 

 tions are localized in definite cortical areas, somewhat after the 

 fashion of a refined and modernized phrenology, and this view is 

 very prevalent among clinical neurologists. 



The modern period of study of cortical functions was inaugu- 

 rated by a chance observation on the battlefield. During the 

 Franco-Prussian war an army surgeon, Fritsch, while operating 

 on a wounded soldier, applied the galvanic electric current to the 

 exposed surface of the brain and observed a twitching of some of 

 the muscles. This was followed immediately by experimental 

 researches upon the electric excitability of the cerebral cortex 

 of dogs, the first results of which were published by Fritsch and 

 Hitzig in 1870. They showed that there are regions in the 

 vicinity of the central sulcus (fissure of Rolando, cruciate sulcus) 

 whose excitation in the living animal is followed by movements 

 of definite groups of muscles on the opposite side of the body. 



These observations have been followed by an immense number 

 of experimental researches on various animals (the animals 

 being anesthetized during the experiments) and clinico-patho- 

 logical studies of the human brain, whose correlation and integra- 

 tion have proved very difficult. The most careful studies have, 

 however, in general given concordant results. Without attempt- 

 ing a summary of these investigations here, we may mention the 

 recent investigations of Sherrington on the chimpanzee, whose 



