37(5 



GANGLION. 



Notwithstanding o many important points 

 have been established, it must be confessed 

 that much remains to be decided. Thus, for 

 example, we perceive that the ganglion of 

 Meckel, like the ganglions of the sympathetic 

 in the neck, has connected with it a motor 

 fibril ; but this fibril, as Arnold has observed, 

 presents the whitish character and firm texture 

 common to the cerebro-spinal nerves, and 

 therefore, it must be presumed, passes from 

 the portio dura to the ganglion, whilst the 

 twigs uniting the cervical nerves and tine 

 sympathetic are reddish and soft, rendering 

 it probable, as Fletcher supposes, that they 

 are furnished by the ganglia. 



Such being the imperfect results of ocular 

 inspection, we are naturally anxious to obtain 

 more exact information, especially in reference 

 to the character of the different orders of fibres 

 which are connected with the ganglia. The 

 microscopical observations which are being car- 

 ried on at this time with so much zeal in Ger- 

 many, and from the prosecution of which the 

 most valuable evidence may be anticipated 

 respecting the undecided points of minute 

 anatomy, have already thrown some light on this 

 interesting question. Thus Ehrenberg* has de- 

 tected in the sympathetic not only the varicose 

 fibres which some imagine are proper to that 

 system, but also some of the cylindrical fibres of 

 which the cerebro-spinal nerves are principally 

 composed. According to Lauth and Remark, 

 the nerves of organic life (i. e. of the sympa- 

 thetic) consist for the most part of varicose 

 fibres mixed up with a small proportion of 

 cylindrical ; whilst those of animal life consist 

 principally of cylindrical mingled with a few 

 varicose fibres. This is the exact appearance 

 which must have been anticipated, if the mu- 

 tual interchange of fibres described by Bichat,f 

 W. Philip,! Mayo, Fletcher,|| and others, 

 really exist. 



It may here be remarked that although the 

 accuracy of Ehrenberg's researches, confirmed 

 as they have been by Miiller, Purkinje, Valen- 

 tin and others, is called in question by Krause, 

 Berres, and Treviranus, yet the essential fact 

 of there being a decided difference in the phy- 

 sical character of different orders of nervous 

 fibres, and, consequently, a test for their suc- 

 cessful analysis, is universally admitted.^ 



Lastly, it is a question of great interest whether 

 there are not, independently of the relations 

 which exist between the sympathetic and the 

 cerebro-spinal axis, fibres proper to the former, 



* L. c. p. 31. 



t An. Gen. i. p. 220. " The ganglions (of the 

 sympathetic) like the brain furnish and receive their 

 particular nerves." 



J On Vital Functions, and Gulstonian Lect. 



$ Out. of Phy. 4th edit. p. 259. 



|| Rud. of Phy. part ii. a. p. 76. 



<|I Since the above was written I have leamt that 

 the doubts expressed by Treviranus, Arnold, and 

 others, as to the correctness of the views of Ehren- 

 berg, have been confirmed. Professor Miiller 

 attributes the appearance of the varicose fibres to 

 artificial causes ; and it is said that Ehrenberg 

 himself doubts if such fibres exist in the normal 

 condition. 



which establish between them and the organs 

 they supply with nerves most important con- 

 nexions. Our present knowledge does not 

 afford the means of solving this question ; and, 

 although my attention has been particularly 

 directed to this subject, still, as my observa- 

 tions are as yet incomplete, I shall satisfy 

 myself by expressing my conviction that such 

 a system of nervous fibres does exist. 



Covering. Every ganglion possesses two 

 coverings : the outer one in the spinal ganglions 

 is very firm, being derived from the vertebral 

 dura mater, whilst in the sympathetic gan- 

 glions it is composed of condensed cellular 

 tissue. On raising very carefully the external 

 capsule, a more delicate tunic is exposed, 

 which adheres to the proper ganglionic tissue. 



Bloodvessels. These bodies, like all other 

 parts of the nervous system, are amply sup- 

 plied with arterial blood. After a successful 

 injection, two, three, or more arteries, derived 

 from the neighbouring vessels, may be readily 

 observed running to the ganglion. Each vessel, 

 having perforated the coverings of the ganglion, 

 forms according to Wutzer a plexus on the inner 

 surface of the capsule, and at length sends de- 

 licate branches into the pulpy matter, which, 

 with the aid of the microscope, may be ob- 

 served to run in the same direction with the 

 nervous filaments. The exact mode in which 

 these vessels terminate is unknown, but it is 

 probable, as in the cerebro-spinal system, that 

 each nervous fibre is accompanied by a mi- 

 nute artery and vein. No lymphatics have 

 been demonstrated, but analogy tends to prove 

 their existence, and Lobstein states that he 

 has often seen them forming networks around 

 the ganglions. 



Chemical composition. The experiments 

 performed by Bichat* and Wutzerf would tend 

 to show that the substance of the ganglions is 

 distinct in its qualities from the cerebral matter 

 and also from that of the nerves. By boiling, it 

 is at first hardened, but soon becomes softened ; 

 maceration in cold water renders it more soft 

 and pulpy, and if sufficiently prolonged, the 

 water being frequently changed, it is converted 

 into adipocire. It is liquefied by the alkalies, 

 and is rendered crisp and hard by the acids 

 and alcohol. 



BIBLIOGRAPHY. Haase, De gangliis nervor. 

 Scarpa, Anat. Annot. Liber i. de nerv. gang, et 

 plexibus. Monro, Obs. on nerv. system. Soem- 

 mering, De corp. hum. fabric, t. iv. Bichat, Anat. 

 gen. Wutzer, De corp. hum. ganglior. fabrica 

 atque usu. This work contains an elaborate list 

 of the various authors who have treated of the 

 ganglions, and an epitome of their opinions. 

 Lobstein, De nervi sympath. humani, fabrica, usu 

 et morbis. F. Arnold, Kopfthiel des Vegetativen 

 nervensystem, beim Menschen. J, Muller, Hand- 

 buch der Physiol. des Menschen, 1834. C. J. Eh- 

 renberg, Structur des Seelenorgans bei Menschen 

 und Thieren, Berlin, 1836 ; Anat. der Microsko- 

 pischen Gebilde der Menschlichen Kbrpers. Wien. 



(R. D. Grainger.) 



* Anat. Gen. t. i. p. 226. 



t De Corp. Hum. Gang. Fabrica atque Usu, 

 $55. The reader will find in this work many* de- 

 tails relative to the above subject. 



