OF THE FUNCTIONS OF THE GANGLIAL SYSTEM- 49 



cumstance of its supplying and actuating the involuntary muscles, that it also bestows 

 its proper influence upon those which are voluntary, and that thus it gives rise, in both, 

 to the phenomenon of muscular parts usually called irritability; the different manifes- 

 tations of this property, as it is displayed in voluntary and involuntary muscles, resulting 

 from the accessory supply of the cerebro-spinal nerves which the former class of mus- 

 cles receives. (See Note F. F.) 



33. That the ganglial system appears to be productive of certain obscure sensations 

 or instinctive impulses (organic sensibility) which are, by means of the communicating 

 branches of nerves between this system and the cerebro-spinal masses, propagated to 

 the latter, and from the influence they there excite, become the cause of several mani- 

 festations, which more immediately proceed from this latter part of the nervous system. 



34. This operation of the ganglial system on the functions of the cerebro-spinal sys- 

 tem is more remarkable when the former is influenced by disease or by a stimulus which 

 is unnatural either in kind or degree ; or even when a natural excitant, to which this 

 system has been accustomed, is withheld, whether such excitant operates either direct- 

 ly or indirectly, or in both ways, as the supply of food, Sec. 



35. The communicating branches of nerves between the chief ganglia of the abdo- 

 minal and thoracic cavities, whilst they are the medium of communication between the 

 ganglial and cerebro-spinal systems, intercept or moderate, by means of the subordi- 

 nate ganglia placed in their course, the influences proceeding from one system to the 

 other. Thus it is that the ganglia in the neck and chest moderate the influence of the 

 functions of the brain on the heart, and that no impulse of the former can reach the lat- 

 ter but through the medium of the ganglia ; and so little are the ganglia influenced by 

 the operations and excitements of the brain, that organic sensibility is only slightly pro- 

 duced by them. If, therefore, the impulses of passion and volition produce but an ob- 

 scure effect upon the ganglia and their chief centre, it is not to be wondered at, that the 

 galvanic influence which must be very considerable to equal the impulses of volition 

 should act comparatively in a very slight and almost insensible manner upon this system, 



36. The ganglia on the communicating branches between the internal ganglia and 

 the spinal cord, intercept the impulses proceeding through this latter channel ; and 

 while they thus moderate the operations of both the brain and spinal marrow upon the 

 internal ganglia!, they seem to generate an influence suited to the intermediate place 

 which they hold. 



37. Irritations of the ganglial system appear to act in a slight and obscure manner up- 

 on the voluntary organs, through the medium of the communicating or conducting bran- 

 ches between this system and the spinal cord; and, but for the ganglia on their course, 

 the irritations of the former, and the impulses of the latter and of the brain, would re- 

 ciprocally act in a manner that would be much more marked, and even in a way that 

 would be injurious to the whole body. 



38. The influence of the ganglial on the cerebro-spinal system, is more marked as 

 the developement and functions of the former system predominate, as in the lo-vver ani- 

 mals and in the foetus of those which belong to the highest orders.* 



* The following outline exhibits a view of the extent of influence which we have at- 

 tributed to the ganglionic system : it formed a part of the contents of a treatise on the 

 anatomy, physiology, and pathology of the ganglionic class of nerves, &c. the publica- 

 tion of which was commenced in the London Medical Repository, but was discontinued 

 in order that it might appear in a separate and extended form. 



"PABT I. comprehends the following sections : 1. A description of the organs ge- 

 nerally called nervous ganglia. 2. An examination into the distribution of their rami- 

 fications, or fibrillae, as far as that has been determined, either by my own, or by the ob- 

 servations of others. 3. Reasons against the usually received opinion, that they consti- 

 tute a part of the cerebral and spinal nerves ; and proofs of their forming a distinct 

 system from the brain, spinal cord, and nerves proceeding from these sources. 4. An 

 account of the connexion existing between the ganglia or their ramifications, and the 

 nervous system, properly so called ; and the mode by which that connexion is eifected. 

 5. An inquiry respecting what viscera and textures they supply. 6. Proofs from the 

 history of the species, and from comparative anatomy, that they form the first eHbrt of 

 organization, and are instrumental in the production of the other textures. 7. Remarks 

 respecting their state during the formation, progress, and decline of the animal. 8. In- 

 ferences from the preceding inquiries. 



" PABT II. The functions of the ganglia considered 1. As they regard the vascular 

 system, on which they are chiefly ramified A. Proofs that the ganglia are the primary 

 and chief source of the heart's action C. Their power over the arterial and capillary 



