SYMPATHETIC NERVOUS SYSTEM. 429 



be treated of fully under the head of the vaso-motor nerves. 

 The mechanism of these movements, however, is peculiar. 

 The action does not immediately follow the stimulation, as 

 it does in the case of the cerebro-spinal nerves and the striated 

 muscles, but is induced gradually, beginning a few seconds 

 after the irritation, endures for a time, and is more or less 

 tetanic. 1 This mode of action is peculiar to the sympathetic 

 nerves and the non-striated muscular fibres. 



"When we remember the invariable connection of the 

 sympathetic ganglia with the cerebro-spinal nerves, we see 

 at once the importance of the question of the derivation of 

 the motor and sensory properties of the ganglionic system. 

 Are the sympathetic ganglia independent nerve-centres, or do 

 they derive their properties from the cerebro-spinal system ? 

 This question may be satisfactorily answered by two kinds 

 of experimental facts : In the first place, section or irritation 

 of the spinal cord and certain of the encephalic centres is 

 capable of influencing the vaso-motor system, a fact which 

 will be dwelt upon more fully in another connection. In 

 the second place, the experiments of Bernard upon the sub- 

 maxillary ganglion and its influence on the secretion of the 

 submaxillary gland have demonstrated, in the most conclu- 

 sive manner, that this ganglion is the centre presiding imme- 

 diately over the reflex phenomena of secretion by the gland ; 

 but it has also been shown that, when all of the connections 

 of the submaxillary ganglion with the cerebro-spinal system 

 are divided, after a few days, this ganglion loses its power as 

 a reflex nervous centre. 8 In the volume on secretion, we 

 have given numerous examples of reflex action through the 

 sympathetic system. 3 The experiments just cited from Ber- 

 nard show that individual ganglia belonging to this system 

 may act independently for a time ; but that this action can- 



1 LEGROS ET OXIMUS, De la contraction des muscles de la vie vegetative. 

 Journal de V anatomic, Paris, 1869, tome vi., p. 433. 



8 BERNARD, RecJierches experimentales sur les nerfs vasculaires et cahrifiques. 

 Journal de la physiologic, Paris, 1862, tome v., pp. 407, 410. 



8 See vol. iii., Secretion, p. 28, et seq. 



