OTHER ASPECTS OF THE FUNCTIONS OF THE BRAIN. 721 



to augmenting or inhibiting the activity of spinal centres. We should, there- 

 fore, hardly expect them to be specially represented in the cortical motor 

 region. But emotions have a much wider and more powerful influence over 

 the splanchnic functions than has the will, and have the power of affecting 

 the work of certain organs, for instance the heart and secreting glands, which 

 the will is unable to touch. And since we have every reason to believe that 

 the cortex is closely associated with the emotions, we may naturally infer 

 that elements of the cortex supply a link in the chain through which an 

 emotion influences this or that splanchnic activity ; we may, 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 vasomotor 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 

 paralyzed side may be as much as 10 C. higher than that of the other side. 

 The effect is partly due to vasomotor 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. 



602. 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 in- 

 trinsic chemical changes, by the metabolism of the cardiac substance ; the 

 influence of external circumstances, apart from those which provide an 

 adequate supply of proper blood, is wholly subsidiary and serves only to 

 raise or to lower the intrinsic changes from time to time, as occasion may 

 demand. And the analogy of the heart has perhaps led us to exaggerate 

 the part played in the brain by the like intrinsic chemical metabolism. 



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