CHAP, ii.] THE BRAIN. 111.-) 



supply a link in the chain through which an emotion influences 

 this or that splanchnic activity; wi- nmy, accordingly, expect to 

 find that stimulation of some part or other of the cortex produces 

 splanchnic effects. The results of experimental investigation, 

 however, are both scanty and discordant ; but the greater weight 

 should perhaps be attached to the positive results. Thus, some 

 observers find that stimulation of the cortex, the locality being in 

 the dog some part of the sigmoid gyrus, produces movements of 

 the bladder ; and they trace the path of this influence through the 

 front part of the thalamus and the tegmentum to the bulb and so 

 to the cord, excluding the cerebellum, which other observers 

 believed to be concerned in the matter. Some observers again find 

 that stimulation of the cortex produces a flow of ' chorda saliva/ 

 while others maintain that the secretion, when it does occur, is an 

 indirect and not a direct effect of the cortical stimulation ; and it 

 may be remarked that the cortical area, which is claimed to be a 

 "salivation area," lying in the dog on the convolutions dorsal to 

 and in front of the Sylvian fissure, is not either the area connected 

 with the facial nerve, or that allotted to taste or smell. 



Similarly, stimulation of parts of the cortex has in the hands 

 of various observers led to movements or to arrest of movements 

 of the intestines, to changes in the beat of the heart, and to 

 various vaso-motor and other effects ; but it will not be profitable 

 to enter into any further details. We may, however, add the 

 remark that when the cortical motor area for a limb is removed, 

 or suffers a lesion, the temporary paralysis which is thereby caused 

 is accompanied by a rise of temperature in the limb ; this may 

 be at times very great indeed ; in the monkey for instance, the 

 hand or foot on the paralysed side may be as much as 5 C. 

 higher than that of the other side. The effect is partly due 

 to vaso-motor paralysis, but, especially considering that the 

 muscles of the limb are relatively quiescent and so producing less 

 heat than usual, cannot be due to that alone. The remarkable 

 result may be taken as still further illustrating the complexity of 

 the processes connected with the cortical motor area ; the area is 

 in some way associated with the vascular arrangements and 

 nutrition of the muscles with whose movements it is concerned. 



690. There remain yet a few words to be said about the* 

 cortex. We regard, and justly so, the spontaneous intrinsic 

 activity of the brain as the most striking feature of its life. The 

 nearest approach to it which we find elsewhere in the body, is 

 perhaps the rhythmic beat of the heart. The analogy between the 

 "regular automatism" of the one, and the " irregular automatism" 

 of the other is a striking one ; and indeed our knowledge of the 

 relatively simple spontaneity of the heart has probably influenced 

 to a large extent our conceptions of the complex spontaneity of 

 the brain. In the heart the rhythmic discharge of energy is 

 chiefly determined by intrinsic chemical changes, by the meta- 



