THE CENTRAL NERVOUS SYSTEM 75^ 



The results of Budgettand Green carry us a step farther and indicate 

 that the function of an efferent, may even be taken on by an afferent 

 nerve. They divided the vagus centrally to the trunk-ganglion, and 

 sutured the peripheral cut end to the peripheral end of the divided 

 hypoglossal. After two or three months, stimulation of the peripheral 

 end of the vagus caused contractions of the muscles of the tongue, 

 apparently due to the excitation of the muscular fibres by impulses 

 reaching them along the formerly afferent vagus fibres. 



The localization of function in the cerebral cortex has been likened 

 to the localization of industries in the multiplex commercial life of 

 the modern world. The barbarian household in which cloth is, 

 woven and worked into garments, sandals or moccasins cobbled 

 together, rough pottery baked in the kitchen fire, and all the rude 

 furniture of the lodge fashioned by the hands which built it, and 

 which rest beneath its roof at night this state of things where? 

 centralization has not yet begun, it has been said, is a picture of what 

 goes on in the undeveloped brains of the frog, the pigeon, and the 

 rabbit. The ' diffusion ' of industries which is characteristic of a 

 primitive state has given place among the most highly civilized men 

 to extreme centralization and concentration. Manchester spins cotton 

 and Liverpool ships it. Chicago handles wheat and pork that have 

 been produced on the prairies of Minnesota and Illinois. Amsterdam 

 cuts diamonds. Munich brews beer. Lyons weaves silk. New York 

 and London are centres of finance. This, it is said, is the picture 

 of the highly specialized brain of a monkey or a man. But ingenious 

 and alluring though such analogies are, they do not rest upon a, 

 sufficient basis of fact. 



It has never been shown nor is it likely that the proof will soon 

 be forthcoming that there is any difference whatever in the physical, 

 chemical or psychical processes which go on in the various centres 

 of the Rolandic cortex. It may be supposed, indeed, that the so- 

 called sensory areas of the cortex differ more widely in their internal 

 activity from the motor areas than the latter do among themselves, 

 and that the activity of the anterior portion of the brain, the portion 

 which has been credited par excellence with psychical functions* 

 differs in kind, not merely in degree, from that of all the rest. But 

 as we have just seen, even the motor areas have sensory functions. 

 A cast-iron physiology may explain this by the assumption of ' sensory* 

 as well as 'motor 5 cells in the Rolandic area, and may find sup- 

 port for such an assumption in the well known fact that the large 

 pyramidal cells whose axons form the pyramidal tract make up but 

 a small proportion of the total number of pyramidal cells in this 

 region, which, besides, contains numerous cells of Golgi's second 

 type (p. 665). Yet there is absolutely nothing to contradict the suppo- 

 sition that the discharge of energy from the most circumscribed 

 motor area or element may be accompanied not only with conscious- 

 ness, but with a high degree of psychical activity. And, indeed, 

 some writers have supposed that such a consciousness of, or even 

 conscious measurement of, the discharge from the motor areas is thq 

 basis of the muscular sense (Bain, Wundt). 



