FUNCTIONS OF THE BRAIN 977 



functional union with the peripheral end of any of the efferent fibres 

 which run from the central nervous system and end in ganglion 

 cells (pre-ganglionic fibres), and the central end of any pre-gan- 

 glionic fibre can do the same with the peripheral end of any efferent 

 somatic fibre (Langley and Anderson). For instance, Langley 

 divided (in cats) the vagus nerve and the cervical sympathetic. 

 The peripheral end of the former degenerated, of course, below the 

 section, and the peripheral (cephalic) end of the latter degenerated 

 above the section, up to the terminations of its axons in the 

 superior cervical ganglion. The central end of the cut vagus was 

 subsequently sutured to the peripheral end of the cut sympathetic. 

 After a time the vagus-fibres grew along the course of the degener- 

 ated sympathetic up to the ganglion, where some of them formed 

 arborizations around the ganglion cells. It was now found that 

 stimulation of the vagus produced the effects usually caused by 

 stimulation of the cervical sympathetic for example, dilatation 

 of the pupil and constriction of the bloodvessels of the head and 

 neck. From these experiments it follows that the functions of the 

 various groups of fibres in the cervical sympathetic do not depend 

 on anything peculiar to the fibres; any fibre which can make con- 

 nection with one of the ganglion cells that send axons to the 

 dilator muscle of the iris will, when stimulated, act as a pupillo % - 

 dilator fibre, just as well as a cervical sympathetic fibre. Other 

 instances of the same law have already been given in connection 

 with the regeneration of nerves (p. 800). 



Functional union does not take place between efferent somatic 

 fibres (or pre-ganglionic fibres) and post-ganglionic fibres i.e., 

 fibres arising in peripheral ganglia, and ending in smooth muscle 

 and glandular tissue; e.g., the cervical sympathetic after excision 

 of the superior cervical ganglion does not unite with the fibres 

 leaving the anterior end of the ganglion in such a way that stimula- 

 tion of it can produce any of the effects normally produced through 

 these fibres. No proof has been given that afferent fibres can unite 

 with efferent fibres or efferent with afferent. 



Afferent fibres of one nerve can unite with afferent fibres of 

 another nerve, but there is not sufficient evidence to show whether 

 fibres concerned in one sensation can unite with fibres concerned 

 in another. 



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 



Eottery baked in the kitchen fire, and all the rude furniture of the lodge 

 ishioned 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 

 Kas 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 



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