1 2 THE IN VOL UNTA R Y NER VO US S YSTEM 



was essentially a system concerned with the innervation of the 

 alimentary canal and its glands. 



Following upon this separation of the two central nervous 

 systems came the separation of the nerve fibres belonging to 

 them, consequent upon the discovery by Remak of non-medul- 

 lated fibres which belonged entirely to the sympathetic system ; 

 later Joh. Miiller, taking into consideration the fact that the 

 rami communicantes were partly grey and partly white, put for- 

 ward the proposition that the white fibres were cerebro-spinal 

 and the grey sympathetic, so that there was a reciprocal con- 

 nexion between the two nervous systems, the animalic centres 

 sending animalic fibres to the organic centres, which in their turn 

 sent organic fibres to the animalic centres. 



Thus Bichat's teaching appeared to be based on the strongest 

 possible foundations of fact, and the absolute independence of the 

 animalic and organic nervous systems established. 



Furthermore the very conception of this separate organic 

 system, together with the position of its main mass in the solar 

 ganglia, firmly inculcated the view that the sympathetic system 

 was essentially connected with the viscera, and even to this day 

 comparative anatomists, on the discovery of nerves going to the 

 intestines of some invertebrate animal, frequently describe them 

 as representing the sympathetic nerves in such an animal. A 

 further extraordinary conception, which arose out of the teaching 

 of the absolute independence of this organic system, and was held 

 somewhat largely, and taught by some anatomists when I began 

 my medical studies, was that the sympathetic system repre- 

 sented the central nervous system of such invertebrates as insects 

 and that the cerebro-spinal system was superadded, being special 

 to the vertebrate. 



Bichat's views were largely prevalent when I took up the 

 question and determined to settle whether there was a reciprocal 

 communication between the two systems. For this purpose I cut 

 serial sections through the rami communicantes and through the 

 roots of the spinal segmental nerve after treatment with osmic 

 acid, and found, as was well known, that the main mass of the 

 non-medullated fibres, after entering the spinal segmental nerve, 

 turned peripheral-wards along the nerve, but that a smaller number 

 proceeded along the roots towards the spinal cord. On tracing 

 these latter, which especially went along the posterior root, they 



