TEOPHIC CENTRES AND NERVES, SO CALLED. 445 



which is the final result of the disease, and these do not 

 involve the action of any special centres or nerves. 



As regards the muscular atrophy itself, if the nervous 

 stimulus be progressively destroyed, the muscular tissue will 

 necessarily undergo degeneration and atrophy. 



AVith the above considerations, we leave the trophic cells 

 and nerves to the pathologist, and can only admit the exist- 

 ence of centres and nerves specially and directly influencing 

 the nutrition of the muscular system, when it has been de- 

 monstrated that there are lesions of particular structures in 

 the nervous system, which produce phenomena that cannot 

 be explained by our knowledge of the action of ordinary 

 motor and sensory nerves and of the vaso-motor system. 1 



AVe have thus endeavored to represent what is actually 

 known concerning the sympathetic system, but it is evident 

 that we have much to learn with regard to its physiology. 

 The great sympathetic ganglia may have functions of which 

 we have no definite idea; and we are better prepared to 

 advance our knowledge in this direction, by admitting our 

 ignorance, than by attempting to supply the deficiencies hi 

 our positive information by theories unsupported by facts. 



1 \Ve have discussed the question of the existence of trophic nerves from a 

 physiological point of view only. In a late review of the subject, by Dr. Hand- 

 field Jones, the same opinion is expressed, based upon pathological arguments, 

 as will be seen by the following quotation : 



" In conclusion, I may state that my review of the subject leads me to dis- 

 credit very much the doctrine that there exists a special class of trophic nerves ; 

 inasmuch as all the phenomena, to explain which their existence might be in- 

 voked, seem to be fairly explicable by alterations in the condition of those 

 which have been long familiar to us." (HASDFIELD JONES, Are there Special 

 Trophi-: Xen-es? St. George's Hospital. Reports, London, 1868, vol. iii., p. 109.) 



