226 JOSEPH DUERSON STOUT 



frequency of the involvement of the two limbs, for the right side 

 an average* of 36 per cent, and for the left side an average of 38 

 per cent of the responses were movements of the fore limb. On 

 the right side an average of 41 per cent and on the left side an 

 average of 47 per cent were movements of the hind limb. This 

 indicates, when the figures are combined, that there is a slightly 

 greater cortical representation for movements of the hind limb 

 than for movements of the fore limb. 



10. Considering the frequency of movements, involving the 

 various joints, it is seen that the joint most frequently involved 

 is the right hind ankle (137 movements), and the next most 

 frequent the right hind knee or right shoulder (each 96 move- 

 ments). The most frequent type of movement is flexion of the 

 right hind ankle (117). 



Extra-motor cortex. From stimulation of the readily approach- 

 able portions of the cortical surface, outside the boundaries recog- 

 nized for the motor area, the following conclusions may be 

 drawn: 



11. More current or longer application of current is required 

 to produce motor activity than is required for successful stimu- 

 lation of the motor area. 



12. The movements so produced are as functionally perfect as 

 are movements produced by stimulation of the motor area. 



13. The latency is always longer with stimulation of these 

 areas. 



14. The movements involve more restricted portions of the 

 body musculature, and are most apt to involve activity of such 

 mechanisms as respiration, pupil changes, chewing, etc. 



15. About 47 per cent of the movements so produced are bi- 

 lateral in their distribution and the others contralateral. 



16. The stimulable extra-motor field occupies a triangular 

 area whose apex approaches the median line near the center 

 of the fissura lateralis, and whose base extends from slightly 

 external to the center of the fissura coronalis, to the point where 

 the supra-Sylvian fissure bends downward posteriorly. Stimu- 

 lation of the major portion of this field results in movements of 

 the eyes and pupils. Several small areas along the supra-Sylvian 



