OF THE FUNCTIONS OF THE GANGLIAL SYSTEM. J5 



Of the Ganglia! or Great Sympathetic System of Nerves. 

 Note H. 



It would be incompatible with the limits of these notes to point out the anatomical 

 peculiarities and connexions of this important system, or even to enter upon a length- 

 ened discussion of their functions. We shall therefore conn' ne ourselves to the state- 

 ment of the general propositions, at which \ve arrived on the latter part of the subject, 

 and which were contained in a paper on the functions of the ganglionic system of nerves, 

 read to the Medical society of London in 1820. 



It may be proper to remark, that these inferences were deduced from numerous dis- 

 sections of individal subjects belonging to the different classes of animals, and from se- 

 veral experiments made in order to ascertain the extent of function which this system of 

 nerves performs. The observations made on these occasions we will soon have an op- 

 portunity of describing in a particular manner. 



1. The ganglial class of nerves is to be found throughout every order of the animal 

 creation, commencing with th'e lowest, the Radiatse, and ascending to the highest. 



2. The ganglial nerves is the only part of the nervous system with which the lowest 

 orders of animals are provided. 



3. As we ascend the scale of creation another class of nerves is superadded, namely, 

 the encephalic, with which the ganglial nerves are connected. In the higher animals 

 possessing only the ganglial nerves, we perceive the ganglial placed on or near the oeso- 

 phagus gradually assuming more and more the characters of a brain, and becoming 

 more evidently connected with organs of sense. We also observe the nervous cords 

 between the ganglia arranging themselves more and more in the manner of a spinal 

 marrow, as the locomotive organs become more distinct from those of nutrition ; thus 

 rendering the steps of gradation between the animals provided only with the lowest or 

 simplest form of nervous ganglia, and those possessed both of ganglia and of animal or 

 voluntary system of nerves, almost imperceptible. 



4. The nerves which are given oft from the encephalic mass and from the spinal mar- 

 row evince different characters as soon as these parts of the nervous system become dis- 

 tinct from the ganglia ; and even in progress towards the fullest distinction which they 

 ultimately attain, the difference between both the classes of nerves becomes still more 

 manifest 



5. In all the more perfect animals, the ganglia and the various distributions, as far as 

 they can be traced by the senses, even when aided by powerful glasses and minute dis- 

 section, are entirely different from the nerves derived from the brain and spinal cord, 

 in their texture, colour, consistence, mode of ramification and distribution ; and they 

 supply very different organs and textures from those to which the cerebral and spinal 

 nerves are distributed. 



6. Not only in the lowest order of animals may the ganglial nerves be traced before 

 the voluntary or sentient class of nerves come into existence, but also in the embryos of 

 the higher animals the ganglia may be distinguished before any traces of a spinal mar- 

 row or of a brain can be perceived. 



7. The ganglial nerves cannot be supposed to originate in either the brain or spinal 

 marrowlet, because they are observed in the lowest animals, who possess neither 

 brain nor spinal cord ; 2dly, because they may be distinguished in embryos before ei- 

 ther the one or the other nervous mass can be traced and Sdly, because they arc- 

 never wanting in the fcctal state, whereas not only have the brain and spinal marrow 

 been individually wanting, but the same foetus has been found entirely without both. 



8. The difference between this class of nerves and those of animal life is not evinced 

 only by their respective appearances, by the general distribution of the former through- 

 out the animal creation, by the history of the embryal foetus, and by the phenomena ex- 

 hibited by monsters, but it is also apparent from the very different 'effects which are ob- 

 served in them, as respects both the living and dead subject, on the application of va- 

 rious excitants and re-agents*. 



* The difference between these nerves is 



nerves is very remarkable on the application of gal- 

 vanism ; for, whilst we found that the voluntary nerves could be excited with a few 

 plates, two hundred could produce only a slightly perceptible effect upon the parts 

 more immediately supplied with fibrills from the semilunar ganglion. When gajranism 

 v/as applied to this ganglion itself in the recently killed animal, but little appreciable 



