1890.] Excitation of Motor Cortex, $c. t in Orang Outang. 159 



4. In spite of their extra-innervation, the abductors of the vocal 

 cords are physiologically weaker than their antagonists. 



5. These antagonists, the adductors of the vocal cords, have pri- 

 marily nothing at all to do with respiration, and ordinarily serve the 

 function of phonation only. Their respiratory functions are limited 

 to 



(a.) Assistance in the protection of the lower air passages against 

 the entry of foreign bodies. 



(6.) Assistance in the modified and casual forms of expiration 

 known as cough and laughing. 



VI. " A Record of the Results obtained by Electrical Excitation 

 of the so-called Motor Cortex and Internal Capsule in an 

 Orang Outang (Simia satyrus)" By CHARLES E. BEEVOR, 

 M.D., F.R.C.P., and VICTOR HORSLEY, B.S., F.R.S. (From 

 the Laboratory of the Brown Institution.) Received 

 June 5, 1890. 



(Abstract.) 



Having been engaged for some time in investigating the representa- 

 tion of motor function in the cortex of the bonnet monkey, we 

 thought it advisable to pei'form the same in an anthropoid as likely 

 thereby to gain a closer insight into the modes of representation in 

 man. 



We first describe the peculiarities noticeable in the configuration of 

 the convolutions in the orang. 



As in the bonnet monkey, after narcotisation with ether, we 

 divided the cortex into squares of 2 millimetres side, and excited the 

 same with minimal stimuli from the secondary coil of an induc- 

 torium. 



General Results. The mode of representation of motor function 

 was found to be highly specialised. The general plan was identical 

 with that seen in the bonnet monkey in that the representation of 

 each segment and part of the body in the orang was arranged in 

 the same order as that according to which we found the representa- 

 tion of the primary movements to be grouped in the macacque 

 monkey. 



In addition to this, the areas for the representation of the different 

 parts of the body we found not to be continuous with each other, but 

 that between the areas of representation (for instance, of the face and 

 the upper limb) there were regions of inexcitable cortex showing 

 a degree of differentiation not obtained in the lower monkey. 



A further remarkable evidence of specialisation was noticeable in 



