THE SYMPATHETIC AND PARASYMPATHETIC SYSTEMS 637 



concluded that these different local reflex circuits are associated by 

 commissural fibers.^ 



Lastly, it should be noted that the afferent impulses of the auto- 

 nomic system may pass into the cerebrospinal system to be received 

 eventually in consciousness (Fig. 314, V). The fact that a path of this 

 kind exists, may be gathered from the work of Dogiel,^ who has found 

 that afferent visceral fibers arise in certain sensory cells of the sympa- 

 thetic system which then enter the posterior root and arborize around 

 the cells of the spinal ganglion. From here these visceral impulses 

 are conveyed inward over the usual afferent tracts of the spinal cord. 

 Thus we may. obtain at times distinct sensations of visceral pressure, 

 pain and temperature, such as arise in the course of the movements 

 of the stomach, intestine, bladder, and other organs. It must be 

 admitted, however, that the viscera are relatively insensitive to ordi- 

 nary stimuli, as may be gathered from the fact that the handling or 

 cutting of internal organs does not give rise to a decided sensation of 

 pain, whereas the mere opening of a body-cavity by an incision through 

 the integument can scarcely be effected without local or general anes- 

 thesia. It should be noted, however, that the sensation of visceral 

 pain need not be restricted to the area in which it has been produced, 

 but may also be projected to the surface layers of the body by way 

 of the corresponding cutaneous somatic fibers. Thus, a diseased organ 

 may give rise to a hypersensitiveness (hyperalgesia) and tenderness 

 to mechanical and thermal stimuli in an area of the integument cor- 

 responding to the distribution of these fibers. As examples of referred 

 visceral pain might be mentioned the radially disseminated pain ex- 

 perienced in the course of the passage of calculi through the biliary 

 ducts or the extreme painful sensations which may be elicited by 

 pressing upon the integument in the region of a gastric ulcer. 



In general, therefore, it may be said that the autonomic system 

 possesses the same functional powers as the cerebrospinal system, be- 

 cause it serves as a : 



(a) Conductor of efferent and afferent impulses, 

 (6) Center for reflex action, 



(c) Tonically automatic center which retains the parts innervated by it in a 

 condition of tonus, and as a 



(d) Center for the regulation of the trophic condition of these parts. 



Pseudo- or Axon-reflexes.^-The question has frequently been 

 asked whether reflexes may also be elicited with the help of single 

 ganglia and their peripheral connections? This should remind us 

 first of all of the controversy pertaining to the nature of the patellar 

 reflex which has finally been decided in favor of the view that it is 

 not an axon-reflex, but is actually effected with the help of the cor- 

 responding spinal center. The only other structure which need be 

 considered in this connection is the spinal ganglion. It has been found 



1 Hoffman, Jahresber. fiir die ges. Med., cclxxi, 1904, 113. 



2 Der Bau der Spinalganglien des Menschen und der Saugetiere, Jena, 1908. 



