266 INDUCTION. 



And for this reason I am not quite prepared to agree with M.Cornte, 

 in deeming the scienpe of society and government intrinsically a more 

 difficult study than the science of organic and animal life. I cannot 

 but incline to the opinion, that physiology is embarrassed by gi-eater 

 natural difficulties, and is probably susceptible of a less degree of 

 ultimate perfectipn, than the social science; 'inasmuch as it is possible 

 to study the laws of one man's mind and actions apart from otlier men, 

 much less imperfectly than we can study the laws of one organ or 

 tissue df 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 experimentatipn properly so called; inasmuch as they 

 often exhibit to us a definite disturbance 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 fimction 

 without ultimately involving many of the others ; and when once it has 

 done' so, the experirnent 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, Ifj 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 tvas 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 disturbance 

 which took place in that part, we are unable to determine wliich 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 Qause. 



Besides natural pathological facts, we can produce pathological facts 

 artificially ; we can try experiments, even in the popular sense of the 

 term, by subjecting the living, being to some external agent, such as 

 the mercury of our former example. As this experimentation is not 

 intended to obtain a direct solution of any practical question, but to 

 discover general laws, from which afterwards the conditions of any 

 particular effect may be obtained by deduction ; the best cases to select 

 are those of which the circumstances can be best ascertained : and 

 such are generally not those in which there is any practical object in 

 view. The exjjeriments are best tried, not in a state iSf disease, which 

 is essentially a changeable state, but in the condition of. health, coxa- 

 paratively a fixed state. In the one, unusual agencies are at work, 

 the results of which we have no means of predicting ; in the otlier, 

 the course of the accustomed physiological phenomena would, it may 

 generally be presumed, remain undisturbed, were it not for the dis- 

 turbing cause vvhich we introduce. 



Such, with the occasional aid of the method of Concomitant Varia- 

 tions (the latter not less encumbered than the more elementary 

 methods, by the peculiar difficulties of the subject), are our indue- 



