i86 



NA TURE 



[Dec. 23, 1886 



supply the lectum, bladder, and reproiiictive organs ; a nerve, 

 therefore, which may be looked upon as the white ramus com- 

 municans of the sympathetic ganglia which form the hypogastric 

 plexus. 



Again, in the cervical region, although such groups of fine 

 fibres are absent from the anterior roots of all the cervical 

 nerves, yet they form a conspicuous part of the upper roots of 

 the spinal accessory nerve, and upon tracing them outwards I 

 find that they separate entirely from the large fibres of the 

 accessory which form its external branch to pass as the internal 

 branch into the ganglion trunci vagi (Fig. 2). Here, then, we 

 see in the upper cervical region that the internal branch of the 

 spinal accessory nerve is formed on the same plan as a white 

 ramus communicans, the ganglion belonging to which is the 

 ganglion trunci vagi. 



Among the cranial nerves we find, especially in the vagus, 

 glosso-pliaryngeal, and chorda tympani, groups of fine nerve- 

 fibres belonging to the same system. We can therefore say that 

 the communication between the so-called sympathetic and 

 cerebro-spinal systems is not symmetrical throughout, but con- 

 sists of three distinct outflows of characteristic visceral nerves, 

 viz. : (l) cervico-cranial ; (2) thoracic ; (3) sacral ; the break of 

 continuity corresponding to the exit of the nerve plexuses which 

 supply the upper and lower extremities. 



These meduUated visceral nerves then pass out from the 

 central nervous system into the various ganglia of the sympa- 

 thetic, and it is possible that these latter ganglia bear the same 

 kind of relation to them as the ganglia on the posterior roots 

 bear to the sensory nerves. Before, however, we can accept 

 this view, it is absolutely necessary to account for the non- 



meduUated nerves which arise from the sympathetic ganglia 

 Now it is hopeless to follow, by anatomical means, any special 

 nerve-fibre through the confusion of a ganglion. What we can- 

 not effect by anatomical methods we can by physiological. If 

 we find two nerves, one of which enters a ganglion and the 

 other leaves it, and we find their function absolutely the same 

 on both sides of the ganglion, we have a perfect right to con- 

 clude that we are dealing with the same nerve in different parts 

 of its course. Thus, in the case of the posterior root ganglion, 

 the same sensory nerves are found on each side of the ganglion, 

 although they are in connection with nerve-cells of the ganglion 

 itself. 



So also with the sympathetic ganglia : we know, for instance, 

 that the nerves which increase the rate and strength of the 

 heart's beat pass to the ganglion stellatum along the rami com- 

 municantes of the second and following thoracic nerves, and we 

 know also that the same nerves pass to the heart from the 

 ganglion stellatum, from the annulus of Vieussens, and from the 

 inferior cervical ganglion. Now, seeing that these nerves are 

 known to pass out of the cord in anterior roots, and from thence 

 into the white rami communicantes of the upper thoracic nerves, 

 it follows that they are meduUated in this part of their cour.-e, 

 and are to be found among the bundles of very fine meduUated 

 nerves which we have seen are characteristic of the anterior 

 roots of this region and of the white rami communicantes. 



We can then say with certainty that the accelerator nerves 

 enter the ganglia stellata as fine white meduUated nerves. I am 

 also able to say with absolute certainty that the accelerator 

 nerves in that part of their course which lies between the chain 

 of sympathetic ganglia and the heart are entirely composed of 



Fig. I. — Diagmm of section of spinal cord to show the 

 sympathetic ganglion, i, cells of posterior horn 

 3. cells of lateral horn and non-ganglionated splanchnic nerves, 

 posterior horn and splanchnic sensory nerves. 



non-medullated fibres. I know no other bundle of nerve-fibres 

 which is so absolutely free from meduUated nerves : in other 

 words, nerve-fibres of the Fame function enter a sympathetic 

 ganglion as white meduUated fibres, and leave it in increased 

 numbers as gray non-medullated nerves. 



Throughout we find the same fact — all the vasomotor nerves 

 behave in exactly the same manner as the accelerators of the 

 heart. In all cases the non-medullated fibres of the sympathetic 

 are simply the fine meduUated visceral nerves which have passed 

 from the spinal cord in one or other of the three visceral out- 

 flows and lost their medullary sheath in their passage through 

 the ganglia of the sympathetic system ; together with that loss 

 of medulla they have increased in mmiber by division. 



Seeing, then, that the non-medullated (so-called sympathetic) 

 nerve-fibres .are throughout modified meduUated (so-called cere- 

 bro-spinal) fibres, and do not, therefore, arise in the sympathetic 

 ganglia, we may fairly look upon the sympathetic ganglia as 

 bearing the same kind of relation to the visceral nerves that the 

 ganglia of the posterior roots bear to the ordinary sensory nerves. 

 This conception is remarkably confirmed by the observations of 

 Onodi, who has shown that the ganglia of the sympathetic are 

 developed in close connection with the posterior root ganglia, 

 and travel further away from the central axis as the animal 

 grows. 



Finally, the meaning of the sympathethic as a simple outflow 

 of ganglionated visceral nerves from certain portions of the 

 spinal cord and medulla oblongata is, to my mind, conclusively 

 settled by the intimate relationship which exists between the 

 structure of the spinal cord and the presence or absence of rami 

 viscerales. In the gray matter of the spinal cord we find, as 



in the gray matter, and the formation of a spinal nerve with its 



2, cells of Clarke's column and ganglionated splanchnic nerves. 



of anterior horn and somatic motor nerves. 5, solitary cells of 



^hown in the accompanying diagram, certain well-defined groups 

 of nerve-cells, viz., a, a group of large nerve-cells in the ante- 

 rior horn (4 in Fig. l) ; these are known to be the origin of 

 ordinary motor-fibres (4) ; l>, a group of nerve-cells (3) split off 

 from this and forming the lateral horn ; i, a group (2) known as 

 Clarke's column ; and d and c, two sets of nerve-cells, (4) and 

 (5), in the posterior horn connected with sensory nerves. 

 All these groups of nerve-cells are found along the whole 

 length of the spinal cord, except those of Clarke's column. 

 Their connection with nerve-fibres of different functions is 

 known, except those of Clarke's column. Thus both sets 

 in the anterior horn are connected with ordinary motor- 

 nerves ; both sets in the posterior horn with ordinary sensory 

 nerves. Now, Clarke's column is limited to certain definite 

 regions of the cord, being conspicuous : firstly, between the 

 second thoracic and second lumbar nerves ; secondly, at the top 

 of the cervical region and extending into the cranial region ; 

 and, thirdly, an isolated patch in the sacral region. In other 

 words, its cells correspond exactly in position to the distribution 

 of the white rami communicantes, so that, corresponding to the 

 variation of this cell-group, we find variations of the number of 

 very fine meduUated fibres in the anterior roots, and we find 

 corresponding variations in the white rami communicantes, 

 which latter, as I have told you, are the only true connections 

 of the cerei;ro-spinal nerve-centre with the sympathetic. In 

 other words, we have driven home to their origin these 

 visceral nerve-fibres, and we find that they do not arise from 

 any nerve-cells outside the brain and spinal cord, but from a 

 definite nerve-group within the spinal cord. 



We can, I think, go further than this, and say, with Bichat, 



