STIMULATING THE MOTOR CORTEX IN ANIMALS. 733 



excitation of the hemisphere produces contraction of muscles of the 

 opposite side of the body, but the parts are too small to determine any 

 exact localisation. 



Of great practical value and interest were the observations which 

 were made by Ferrier upon the brain of the monkey, in which the 

 chief features of the conformation of the cerebral surface are so closely 

 similar to those of the human brain, that it is possible to draw 

 conclusions as to localisation of function in man, such as cannot well 

 be done from experiments upon carnivora. The advantage of the 





FIG. 332. Diagram showing the results obtained by Ferrier on stimulation 

 of the cerebral cortex of the dog. A, Sylvian fissure ; B, crucial sulcus, 

 with sigmoid gyrus curving round it ; 0, olfactory lobe ; I, II, III, IV, 

 first, second, third, and fourth external gyri ; l of these the first is 

 continued anteriorly into the sigmoid (see Fig. 331); the second, third, 

 and fourth blend in front to form the anterior composite gyrus. 2 

 1, Opposite hind-limb advanced; 3, tail moved laterally; 4, retraction 

 and adduction of opposite fore-limb ; 5, protraction of opposite fore- 

 limb with elevation of shoulder ; X, between 4 and 5, flexion of paw ; 

 7, closure of opposite eye and movement of eyeballs ; 8, retraction and 

 elevation of opposite angle of mouth; 9, opening of mouth and move- 

 ments of tongue (sometimes accompanied by barking) ; 11, retraction 

 of angle of mouth on both sides, and ear drawn forwards ; 11' (same 

 as 7), closure of opposite eye; 12, eyes open, pupils dilate, eyes and head 

 move to opposite side ; 13, eyes (and head) move to opposite side ; 14, 

 pricking, or sudden retraction, of opposite ear ; 15, torsion of nostril 

 on same side ; 16, elevation of upper lip and dilatation of nostrils. 



selection of monkeys as the subjects of experiment upon the brain, was 

 immediately made evident by the precise results which were obtained 

 as the result of stimulation of the cortex, and by the far-reaching effect 

 which such experiments have had upon the diagnosis and surgical treat- 

 ment of brain affections in man. The results obtained by Terrier from 

 stimulation of the Eolandic area of the monkey's brain are shown in 

 Fig. 335. Ferrier's main results have been confirmed by many observers, 3 



1 This is Ferrier's nomenclature ; by Leuret and Gratiolet the enumeration was taken 

 from below up. 



2 Langley, Journ. Physiol., Cambridge and London, vol. iv. p. 248. In this paper will 

 be found a full account of the fissures and convolutions of the dog's brain, and of the 

 nomenclature which has been adopted by various authors. 



3 E.g. H. Munk, various papers in Verhandl. d. physioL Gesellsch. zu Berlin, Arch, 

 f. PhysioL, Leipzig, collected in Ges. AbhandL, 1890; also in Ber. d. Tc. Akad. d. 



Wissensch. zu Berlin ; Horsley and Schafer, Proc. Roy. Soc. London, 1884 ; Phil. Trans. , 

 London, 1888, B ; and Festschr. z. Carl Ludwig, 1887 ; Beevor and Horsley, Phil. Trans., 

 London, 1887 and 1888, B ; A. Biedl, Wien. Iclin. Wchnschr., 1897, S. 635. 



