538 INDUCTION. 



the laws of one organ or tissue of the human body 

 apart from the other organs or tissues. 



It is profoundly remarked by M. Comte, that 

 pathological facts, or, to speak in common language, 

 diseases in their different forms and degrees, afford in 

 the case of physiological investigation the nearest 

 equivalent to experimentation properly so called ; 

 inasmuch as they often exhibit to us a definite disturb- 

 ance in some one organ or organic function, the 

 remaining organs and functions being, in the first 

 instance at least, unaffected. It is true that from 

 the perpetual actions and reactions which are going 

 on among all the parts of the organic economy, there 

 can be no prolonged disturbance in any one function 

 without ultimately involving many of the others ; and 

 when once it has done so, the experiment for the 

 most part loses its scientific value. All depends upon 

 observing the early stages of the derangement; which, 

 unfortunately, are of necessity the least marked. If, 

 however, the organs and functions not disturbed in 

 the first instance, become affected in a fixed order of 

 succession, some light is thereby thrown upon the 

 action which one organ exercises over another ; and 

 we occasionally obtain a series of effects, which we 

 can refer with some confidence to the original local 

 derangement ; but for this it is necessary that we 

 should know that the original derangement was local. 

 If it was what is termed constitutional, that is, if 

 we do not know in what part of the animal economy 

 it took its rise, or the precise nature of the disturb- 

 ance which took place in that part, we are unable to 

 determine which of the various derangements was 

 cause and which effect; which of them were produced 

 by one another, and which by the direct, though 

 perhaps tardy, action of the original cause. 



