868 A MANUAL OF PHYSIOLOGY 



been taken of this in surgery. For instance, in a case of severe 

 facial (motor) tic the facial nerve was divided and its peripheral 

 end united with a portion of the fibres of the spinal accessory. 

 The voluntary movements of the face, after regeneration had 

 occurred, were normally carried out through impulses descending 

 the spinal accessory. In cases of local paralysis, due to destruc- 

 tion of anterior horn-cells (anterior poliomyelitis), restoration of 

 movement has also been obtained by connecting the motor nerve 

 of the paralyzed muscles to a portion of a nerve coming off from 

 an uninjured region of the cord. 



The central end of any efferent somatic fibre can also make 

 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-ganglionic 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 de- 

 generated, 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 degenerated sympa- 

 thetic up to the ganglion, where some of them formed arboriza- 

 tions around the ganglion cells. It was now found that stimula- 

 tion 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 connection 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. 696). 



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 

 stimulation 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 



