220 JOSEPH DUERSON STOUT 



the discontinuance of the stimulation and that stimuli at these 

 points are not followed by after-movement. A condition similar 

 to that mentioned by Frangois-Franck would be expected from 

 stimulation of the subcortical tissue. The absence of it indi- 

 cates a very close (and, perhaps frequent) connection between 

 the cortex and the immediately underlying tissue, a connection 

 even closer than the connection between the cortex and the 

 corona radiata. 



The presence of after-movement in the contractions resulting 

 from the stimulation of the subcortical tissues in the cat may, 

 however, be due to the fact that the cat is lower in the scale 

 than the monkeys with which Frangois-Franck worked, and 

 that in the cat the dependence of the lower centers is not so 

 marked. It may then be that the lower centers once set into 

 activity are capable of continuing their motor discharges for a 

 certain time, in the form of after-movement in the cat while in 

 the monkey the dependence of the lower centers is such that they 

 cease activity immediately on the discontinuance of the dis- 

 charges from the higher centers. This presupposes that the 

 after-movement present from the stimulation of the intact cor- 

 tex of the monkey is a purely cortical phenomenon. A somewhat 

 similar amount of independence of the cortex and the subcortical 

 parts in the dog, as compared with the monkey, is indicated in 

 the relative ease of recovery of the dog and the relative diffi- 

 culty of recovery in the monkey after the experimental produc- 

 tion of a cortical hemiplegia. 



MOTOR REACTIONS FROM STIMULATION OF THE CORPUS CALLOSUM 

 AND THE CORONA RADIATA 



Tests of the irritability of the corpus callosum and the corona 

 radiata in cats 18, 21, 26, 27, and 32 were performed as follows: 

 The superior surface of the cortex of the left hemisphere was 

 removed in a long wedge-shaped strip, extending from the 

 occipital pole to the superior end of the supraorbital fissure 

 and from the lateral fissure to a line projected posteriorly from 

 the outermost portion of the coronal fissure. The tissue re- 



