230 Dr. D. Ferrier on the [Mar. 5, 



tracts, is considered to be disposed of by the fact of the precision and pre- 

 dictable characters of the results, and by the marked differences in the 

 phenomena which are observed when regions in close local relation to 

 each other are excited. Other facts are pointed out bearing in the same 

 direction ; among others, the harmony and homology subsisting between 

 the results of experiment in all the different animals. 



The experiments on monkeys are first described. 



Reference is continually made in the description to figures of the brain, 

 on which are delineated the position and extent of the regions, stimula- 

 tion of which is followed by constant and definite results. A complete 

 statement of these results in the present abstract is impossible. 



Generally, it may be stated that the centres for the movements of the 

 limbs are situated in the convolutions bounding the fissure of Rolando, 

 viz. the ascending parietal convolution with its postero-parietal termina- 

 tion as far back as the parieto-occipital fissure, the ascending frontal, and 

 posterior termination of the superior frontal convolution. Centres for 

 individual movements of the limbs, hands, and feet are differentiated in 

 these convolutions. 



Further, in the ascending frontal convolution, on a level with the pos- 

 terior termination of the middle frontal, are centres for certain facial 

 muscles, e. g. the zygomatics &c. At the posterior termination of the 

 inferior frontal convolution and corresponding part of the ascending 

 frontal are the centres for various movements of the mouth and tongue. 

 This is the homologue of " Broca's convolution." At the inferior angle 

 of the intraparietal sulcus is the centre for the platysma. 



In the superior frontal convolution, in advance of the centre for cer- 

 tain forward movements of the arm, as well as in the corresponding part of 

 the middle frontal convolution, are areas, stimulation of which causes lateral 

 (crossed) movements of the head and eyes and dilatation of the pupils. 



The antero-frontal region, with the inferior frontal and orbital convo- 

 lutions, give no definite results on irritation. Extirpation of these parts 

 causes a condition resembling dementia. 



No results could be ascertained as regards the function of the central 

 lobe or island of Reil. 



Irritation of the angular gyrus (pli courle) causes certain movements 

 of the eyeballs and pupils. Destruction of this convolution gives data 

 for regarding it as the cerebral expansion of the optic nerve, and, as such, 

 the seat of visual perception. 



The phenomena resulting from irritation of the superior temporo- 

 sphenoidal convolution (pricking of the ear, &c.) are indications of exci- 

 tation of ideas of sound. It is regarded as the cerebral termination of 

 the auditory nerve. The sense of smell is localized in the uncinate con- 

 volution. The situation of the regions connected with sensations of 

 taste and touch is not accurately defined, but some facts are given indi- 

 cating their probable locality. 



