THE BIOLOGICAL SCIENCES AND MEDICINE. 807 



lie formed by a few billion *' animulse " for the moDarchy of the all- 

 pervading "anima." 



Others, on the contrary, supported by a robust faith in the univer- 

 sal applicability of the j^rinciples laid down by Descartes, and seeing 

 that the actions called " vital " are, so far as we have any means of 

 knowing, nothing but changes of place of particles of matter, look to 

 molecular physics to achieve the analysis of the living protoplasm itself 

 into a molecular mechanism. If there is any truth in the received 

 doctrines of physics, that contrast between living and inert matter, on 

 which Bichat lays so much stress, does not exist. In nature, nothing- 

 is at rest, nothing is amorphous ; the simplest particle of that which 

 men in their blindness are pleased to call "brute matter" is a vast 

 aggregate of molecular mechanisms, performing complicated move- 

 ments of immense rapidity and sensitively adjusting themselves to 

 every change in the surrounding world. Living matter differs from 

 other matter in degree and not in kind ; the microcosm repeats the 

 macrocosm ; and one chain of causation connects the nebulous original 

 of suns and planetary systems with the protoplasmic foundation of life 

 and organization. 



From this point of view, pathology is the analogue of the theory 

 of perturbations in astronomy ; and therapeutics resolves itself into 

 the discovery of the means by which a system of forces competent to 

 eliminate any given perturbation may be introduced into the economy. 

 And, as pathology bases itself upon normal physiology, so therapeu- 

 tics rests upon pharmacology ; which is, strictly speaking, a part of 

 the great biological topic of the influence of conditions on the living 

 organism and has no scientific foundation apart from physiology. 



It appears to me that there is no more hopeful indication of the 

 progress of medicine toward the ideal of Descartes than is to be de- 

 rived from a comparison of the state of pharmacology, at the present 

 day, with that which existed forty years ago. If we consider the 

 knowledge positively acquired, in this short time, of the modus ope- 

 randi of urari, of atropia, of physostigmin, of veratria, of casca, of 

 strychnia, of bromide of potassium, of phosphorus, there can surely be 

 no ground for doubting that, sooner or later, the pharmacologist will 

 supply the physician with the means of affecting, in any desired sense, 

 the functions of any physiological element of the body. It will, in 

 short, become possible to introduce into the economy a molecular 

 mechanism which, like a very cunningly contrived torpedo, shall find 

 its way to some particular group of living elements, and cause an ex- 

 plosion among them, leaving the rest untouched. 



The search for the explanation of diseased states in modified cell- 

 life ; the discovery of the important part played by i^arasitic organ- 

 isms in the etiology of disease ; the elucidation of the action of medi- 

 caments by the methods and the data of experimental physiology ; 

 appear to me to be the greatest steps which have ever been made 



