170 



consequently that the secondary change must happen by communica- 

 tion, and not by privation of properties. 



3. As the cases just referred to are among the commonest we 

 are called upon to witness, it is to be inferred that the communion 

 between parts may subsist without dependence, so that an injury in 

 one seat may destroy in another, by the derangement imparted from 

 the tirst to the second : thus a ligature on a superior part of a 

 nerve may produce a sloughing of the inferior, while no such effect 

 will follow a simple division. Hence injuries are no proofs of de- 

 pendence, although they have been confounded with others as such. 



4. But the results of simple division in general will indicate a 

 dependence, because it is not the common effect of division to im- 

 pair the properties of remote parts by communication of influence. 

 Not but this may happen, and the cases have been adverted to in 

 which it does happen; but, weighing the larger portion of our ex- 

 perience against the smaller, we are, according to the right of 

 inference, justified in thinking, when certain properties, making its 

 function in an inferior part, as of a nerve, cease in consequence of a 

 simple division, that then the inferior part is dependent upon 

 the superior for those properties. But of what kind, or how far 

 they may be possessed in common |>y other substances, entitling 

 them merely to the appellation of stimuli, is neither discovered nor 

 sought for. A determined scepticism may oppose both the above 

 conclusions and the general sense of mankind, upon the same cases; 

 it may urge, that under the change which a portion of a nerve un- 

 dergoes by an injury, &c. this local state of the nerve may open a 

 relation with the brain, by which the latter acquires or derives pro- 

 perties from the former, thus identifying or constituting pain, and 

 other phenomena of such injuries, by the properties of a nerve, 

 which remain after some are taken away. 



5. As the mere existence of organic life is not directly dependent 

 upon any other seat than that in which it assimilates; so if the 

 organic life is modified or ceases in a secondary seat, as a conse- 

 quence of a primary injury, it is by a communication of propertiet 

 through connected tpheres. 



