THE NERVOUS SYSTEM. 441 



that it has ever been absent. The heart never exists without its 

 ganglion; so that the cardiac ganglion, as the heart is the first 

 organ that comes into action, is the commencement of the nervous 

 system. 



A striking difference is observed in the structure of ganglionic 

 nerves and the effect of injuries upon them. Bichat asks, " What 

 anatomist has not been struck with the difference between the 

 cerebral and ganglionic nerves ? Those of the brain are larger, 

 more numerous, whiter, denser, subject to fewer variations. On 

 the other hand, extreme tenuity, considerable number, especially 

 at the plexuses, a grey colour, remarkable softness, and very 

 frequent varieties, are the characters of the ganglionic nerves, 

 if you except those which communicate with the cerebral, and 

 some of those which unite" the ganglia. r 



If these nerves are cut, or their ganglia torn, some assert that 

 no pain is produced. Dr.Brachet declares that he found the spinal 

 nerves running to the sympathetic ganglia to be very sensible : 

 the nerves running from and between ganglia to be insensible, 

 unless inflamed, and, when inflamed, to become sensible, but at the 

 inflamed point only, and to lose their sensibility again if the twigs 

 of communication with the spine were divided: a ganglion to 

 be sensible or insensible accordingly as a point in it was touched 

 or not in which a spinal nerve ran, and to lose all sensibility on 

 the division of the nerve connecting it with the spine ; to be very 

 sensible if inflamed, but insensible again on the division of the 

 spinal nerve. 8 If all the ganglia of the neck are removed, and 

 even the first thoracic, Dr. Magendie says that no sensible or im- 

 mediate derangement of the functions is observable, even in parts 

 to which the filaments united with them may be traced. l Bichat 

 long since remarked no disturbance of the' heart's motion on at- 

 tempting to irritate, or on dividing, the cardiac filaments of the 

 sympathetic ; nor of the stomach, bladder, &c. by applying vio- 

 lence or stimuli to their ganglionic nerves. Neither did he suc- 

 ceed with galvanism": but Humboldt and Dr. Fowler, Home and 



r Recherches Pliysiologiques, p. 72. sq. 1805. See also Anat* Generate, t. i. 

 p. 222. 



See also Gall, 1. c. 4to. vol. i. p. 40. sqq., 8vo. t. vi. p. 312. 



Dr. Magendie, Precis Element, t. i. p. 171. sq, 



3 1. c. p. 304. sqq. 



1 Dr. Magendie, 1. c., says he has made these experiments repeatedly. 



u 1. c. 334. sqq., 360. sqq. 



