356 THE BIOLOGICAL SCIENCES AND MEDICINE. 



and planetary systems with the protoplasmic foundation 

 of life and organisation. 



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 elimi- 

 nate any given perturbation may be introduced into the 

 economy. And, as pathology bases itself upon normal 

 physiology, so therapeutics 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 indica- 

 tion of the progress of medicine towards the ideal of 

 Descartes than is to be derived 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 operandi 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 doubt- 

 ing 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 

 explosion among them, leaving the rest untouched. 



