THE MOTOR CENTERS AND THE WILL. 105 



" ascending parietal " convolutions. Now here, at the lowest end of 

 the fissure of Rolando, we find motor areas for the movement of both 

 sides of the face : that is to say that, as regards this particular piece 

 of the cortex, it has the power of moving not only its regular side of 

 the face, the right, but also the left — that, in fact, both sides of the 

 face move by impulse from it. 



Higher up we find an area for movement of the opposite side of 

 the face only. I reserve for a moment the description of this portion 

 of the brain, and pass on to say that above these centers for the face 

 we find the next is for the upper limb, and most especially the com- 

 mon movement of the upper limb — viz., grasping, indeed the only for- 

 ward movement which the elbow is capable of, namely, flexion. The 

 grasping and bringing of an object near to us is the commonest move- 

 ment by far, and we find here that this center is mainly concerned in 

 it. Behind the fissure of Rolando, Dr. Ferrier placed the centers 

 for the fingers. Next above the arm area is a portion of the cortex 

 which moves the lower limb only, and in front of this again is an area 

 for consonant action of the opposite arm and leg. Let me here remind 

 you that this being the left hemisphere, these are the centers for move- 

 ment of the opposite, that is, the right limbs, and that in the other 

 hemisphere there are corresj^onding areas for the left limbs. 



Thus here we have mapped out those portions of the cortex which 

 regulate the voluntary movement of the limbs. So far I have omitted 

 mention of the muscles of the trunk, namely, those which move the 

 shoulders, the hips, and bend and straighten the back. Dr. Ferrier 

 had shown that there existed on the outer surface of the cortex, here, 

 a small area for the movement of the head from side to side. 



Professor Schafer and myself have found that the large trunk- 

 muscles have special areas for their movement, ranged along the margin 

 of the hemisphere, and dipping over into the longitudinal fissure. Thus 

 all the muscles of the body are now accounted for, and I will first draw 

 special attention to the fact that they are arranged in the order, from 

 below upward, of face, arm, leg, and trunk. 



The consideration of this very definite arrangement led Dr. Lauder 

 Brunton to make the ingenious suggestion that it followed as a neces- 

 sary result of the progressive evolution of our faculties. For, premis- 

 ing, in the first place, from well-ascertained broad generalizations, that 

 the highest center, physically speaking, is also the highest functionally 

 and most recent in acquirement, we find that the lowest is the face, 

 and then we remember that the lowest animals simply grasp their food 

 with their mouth. I imagine it is scarcely necessary for me to repeat 

 the notorious confession that our faculties are arranged for the pur- 

 pose of obtaining food as the primary object of what is called bare 

 existence. 



Proceeding upward in the scale of evolution, we next find animals 

 which can grasp their prey and convey it to the mouth, and so we find 



