574 THE NEEYOTTS SYSTEM. 



its trunk, the levator palati and azygos uvula), to which 

 its filaments probably pass through the spheno-palatine 

 ganglion, do not contract. 



We may account for these facts, by believing that the 

 impression, whether of the mind or of artificial irritation, 

 which would be conveyed at once through nerve-fibres, 

 unconnected with ganglia, is, in the ganglia of the sym- 

 pathetic, communicated and diffused among the corpuscles 

 and the other fibres; and thus, as one may say, is ex- 

 hausted without reaching the muscles, or, in the case of a 

 centripetal nerve, the spinal cord or brain. 



Whether, then, the conduction be effected through 

 proper sympathetic nerve-fibres, or through cerebro- spinal 

 fibres mingled with them and traversing their ganglia, 

 there is this peculiarity to be ascribed either to the fibres 

 or, more probably, to the ganglia that the conduction is 

 effected more slowly ; so that when, for example, a gan- 

 glion on a sympathetic nerve is irritated, the movements 

 in the parts supplied from it do not immediately ensue, 

 and pain is not indicated till after repeated irritations, 

 or till, by exposure or otherwise, the fibres and ganglia 

 have become morbidly irritable. But, with this exception, 

 it is probable that the laws of conduction of impressions 

 are the same in both cerebro-spinal and sympathetic 

 systems. 



^Respecting the general action of the ganglia of the 

 sympathetic nerve little need be said here, since they may 

 be taken as examples by which to illustrate the common 

 modes of action of all nerve-centres (see p. 485). Indeed, 

 complex as the sympathetic system, taken a6 a whole, is, 

 it presents in each of its parts a simplicity not to be found 

 in the cerebro-spinal system : for each ganglion with 

 afferent and efferent nerves forms a simple nervous system, 

 and might serve for the illustration of all the nervous 

 actions with which the mind is unconnected. But it will 



