THE FUNCTIONS OF THE NERVOUS SYSTEM. 277 



tributes to the power of the ganglionic system originates. Vital organs ai-e 

 equally connected with every part of the brain and spinal marrow ; and if we 

 must not look for those partial sympathies with respect to their other functions, 

 there is still less room, it is evident, to look for them in those functions where 

 the sensoiial power is concerned. 



The sensorium evidently residing and operating at the source of nervous 

 power, there receives the various impressions conveyed by the nerves, and 

 there influences those nerves which convey its dictates. 



I shall beg leave to conclude this paper with a short recapitulation of the 

 principal points which appear to be ascertained by the experiments referred to 

 in it. 



The nerves are divided into two classes, whose functions essentially differ ; 

 those proceeding directly from the brain and spinal marrow, which, in the one 

 direction, convey the influence of the parts of those organs from which they 

 have their origin, and are the sole means of exciting the muscles of voluntary 

 motion ; and in the other, impressions which influence the sensorium : and the 

 ganglionic nerves, which, while they also convey impressions to the sensorium 

 and occasionally excite the muscles of involuntary motion, usually excited by 

 stimuli peculiar to themselves, have for their principal function one of greater 

 importance, and which requires the combined influence of the whole brain and 

 spinal marrow, that of supporting the various processes of secretion and assi- 

 milation, and are consequently in the strictest sense a vital organ. 



Although the nervous power therefore stands only in the relation of a sti- 

 mulus to the muscular fibre, whether of voluntary or involuntary motion, in 

 no degree contributing to its power, which depends on its own mechanism ; 

 it is essential to the existence of the secreting and assimilating powers, which 

 are immediately destroyed by withdrawing its influence. 



Such is the relation which the nervous system bears to what may be termed 

 the circumference of the animal body, in contradistinction to the sensorium, 

 which may be justly regarded as its centre, to which that system bears a re- 

 lation of equal importance ; for it may be regarded as the means of connecting 

 the organs of the sensorium with all other parts. In its power this system 

 is independent of the sensorium, for we have seen it capable of all its func- 

 tions after the sensorial power is withdrawn ; but in all of them it is in- 



