1893.] 



On the Cortex Cerebri in the Monkey, 



463 



III. " A Further Minute Analysis by Electric Stimulation of the 

 so-called Motor Region (Facial Area) of the Cortex Cerebri 

 in the Monkey {Macacus sinicus)." By Charles E. BEEVOR, 

 M.D., F.R.C.P., and Victor Horsley, M.B., F.R.C.S., F.R.S. 

 Received March 22, 1893.* 



(From the Laboratory of the Brown Institution, and from the Pathological 

 Department of University College, London.) 



(Abstract.) 



In the paper of which this is an abstract the authors have com- 

 pleted the minute analysis of the movements elicited by excitation of 

 the excitable (so-called motor) region of the cortex cerebri in the 

 Bonnet Monkey {Macacus sinicus). The portions hitherto examined 

 having been those in which the movements of the limbs were repre- 

 sented, the facial area was chosen for the present research. After an 

 historical introduction and a description of the anatomy of the 

 region investigated, the method of notation and record of results is 

 discussed. 



Considering that in this part of the cortex cerebri there is well- 

 defined representation of movements of both sides of the body, the 

 question of bilaterality of representation is raised, and attention 

 directed to its importance. The analysis of the results obtained 

 showed that there existed precise localisation for the movements of 

 the individual portions of the face, even to that of half the lower lip. 



The specialisation of the movements of the toDgue was rendered 

 easy of examination by employing the operative device of dividing 

 the tongue in the middle line. This shed unexpected light on the 

 representation of the movements of this organ. 



Movements of the pharynx were made the subject of observation, 

 and some degree of unilaterality was discovered in the movements of 

 the soft palate. 



Finally, attention is drawn to the fact that the marches of move- 

 ments in succession are in this region very inconstant and difficult to 

 arrange. 



* The expenses of this research were defrayed principally by a grant from the 

 Government Grant Fund of the Royal Society, and in part by a grant from the 

 Scientific Grants Committee of the British Medical Association. 



