260 SIR CHARLES BELL ON THE RELATIONS BETWEEN 



jected in different directions, and belong to distinct filaments*, they must be finally 

 conjoined and in union. The anatomy conforms to this idea ; the cords of com- 

 munication between the seat of volition and the organs of the body proceed from 

 a centre, run parallel, undergo similar changes, and are blended in their ultimate 

 distribution, as in their central or cerebral relations. 



It is pleasing to see that through the labours of members of this Society the prin- 

 ciples which have directed the author in the investigation of the human anatomy 

 are likely to be extended in their application, by a correspondence being observed in 

 the arrangement of the nervous tracts through every class of animals possessing 

 volition. It has long appeared to the author that the system does not differ, even in 

 the different classes of animals, although there is much apparent variety in the 

 distribution of the nerves. 



When it became a question whether or not Crustacea possessed the organ of 

 hearing, the celebrated Scarpa undertook the investigation. With this purpose he 

 did not pry about to discover the external organ of the sense. He looked to the brain, 

 or cerebral ganglion, — recognised the part from which the acoustic nerve should 

 come, according to the analogy of other animals. He found the nerve, and traced it 

 to its destination ; that simple rather than imperfect organ, which, but for the cir- 

 cumstance of the auditory nerve in its cavity, might have been supposed too defective 

 in its organization to be capable of receiving the impulse of sounds. 



In this manner is the nervous system to be studied ; for there is an internal change, 

 in accordance with outward organization, whilst the system or great plan does not 

 vary. There is an endowment in each particular column ; it is one through its whole 

 course. An animal, or a class of animals, may have a particular organ developed, 

 and with the external apparatus there is a corresponding or an adjusted condition of 

 the appropriated nerve. Another class may be deficient in the external organization, 

 when we shall in vain look for the accompanying nerve ; it is contracted, or hardly 

 visible ; but with all this the system is unchanged. 



From a more cursory view of the comparative anatomy than others may have taken, 

 this is my conclusion ; but my time for such investigations has been given almost 

 exclusively to the human anatomy ; and in it I hope it will be granted that the 

 system, as it regards sensation and motion, has been displayed so as to increase the 

 interest of these pursuits, and to direct the studies of the pathologist to beneficial 

 results ; much advantage could hardly have been expected by dissection of the brain, 

 even from the utmost ingenuity of research, whilst the very elements of the subject, 

 as regards the natural anatomy, were unknown. 



* See the paper on the Nervous Circle. 



