1893.] of the Sympathetic Nervous System. 553 



it indicates that the connexion of the spinal nerve with the gang- 

 lion has been determined, not by pilo-motor, but by some other, 

 fibres. 



The facts given in the table, together with those given earlier 

 regarding the distribution of the rami of the ganglia, show the 

 areas of the skin which are supplied by the pilo-motor fibres issuing 

 from the cord in the roots of each spinal nerve given in the table. 



Can we from these data deduce any conclusions with regard to the 

 distribution of the other sympathetic fibres of the spinal nerves ? 



I have said that the pilo-motor fibres to the skin over the vertebrae 

 run to the periphery in the dorsal cutaneous branches of the spinal 

 nerves. It is easily shown that the area of the skin supplied with 

 pilo-motor fibres by the dorsal cutaneous branch of any given spinal 

 nerve is also supplied by it with sensory fibres. And I think there 

 is good reason for believing that the fibres of the grey ramus of a 

 nerve, i.e., the post-ganglionic sympathetic fibres of a spinal nerve, 

 have, in the main, the same distribution in the skin as the sensory 

 fibres of the nerve. 



The chief physiological observations on the distribution of sensory 

 fibres in the skin are those of Tiirck,* made on the dog, and of 

 Sherrington,f made on the monkey. These observations give the 

 sensory areas of both dorsal and ventral cutaneous branches. To 

 compare with these, we have the pilo-motor nerves of a portion of 

 the dorsal cutaneous branches, and the secretory nerves of certain 

 ventral cutaneous branches running to the hind foot.J There would 

 be no advantage in attempting here to discuss in detail the degree of 

 coincidence in the areas of the sensory and of the visceral fibres, and 

 chiefly because, in many cases at any rate, a given spinal nerve in any 

 one of the animals has not an exactly corresponding spinal nerve in the 

 other two animals. But, in iny opinion, the correspondence in the 

 areas of the sympathetic and the sensory fibres, so far as we know 

 them, is close enough to justify the conclusion that the sensory and 

 the post-ganglionic sympathetic fibres in any spinal nerve have, in the 

 main, the -same distribution. The chief point which may be urged 

 against this view is that, according to Sherrington, the areas of the 

 sensory fibres of the dorsal and upper lumbar spinal nerves largely 

 overlap. An overlapping of pilo-motor fibres as great as that found 

 by him for sensory fibres has not occurred in my experiments. On 

 the other hand, it is to be remembered, that in my experiments 



* Tiirck, ' Sitzungsb. d. Wiener Akad.,' vol. 21, 1856 ; and ' Denkschrift. d. 

 Wiener Akad.,' vol. 29, 1869. 



f Sherrington, ' Roy. Soc. Proc.,' vol. 52, p. 333, 1893. 



I ' Journ. of Physiol.,' vol. 12, p. 347, 1891. 



Tiirck did not find overlapping, or only slight overlapping, in the nerves of the 

 neck and trunk. 



