MODERN METHODS OF MEDICAL SCIENCE 35 



provided this be not too injurious, and that the medical art can be 

 more successfully exerted in preventing disease than in its cure. 

 The first effect of increased knowledge of disease was to produce 

 a feeling of powerlessness in the face of it, followed by a nihilism 

 in therapeutics which was as much to be deplored as overconfidence, 

 for it acted as a bar to progress. This nihilism was a prominent 

 feature of the Vienna school in the sixth decade of the past century. 

 The science of therapeutics as we find it to-day is founded on ex- 

 perimental pharmacology and pathology. In experimental pharma- 

 cology the action of drugs on the healthy animal is investigated. 

 It is sought to discover the mode of entry of the drug into the tissues, 

 the mode of excretion, the changes the drug undergoes while in 

 the body, and the changes in structure and function it produces. 

 The action of the drug may differ in different animal species. Know- 

 ledge of the pathology of disease shows in what part changes are 

 produced by the causative agent, the nature of the changes, and 

 the effect of these changes on function. The determination of what 

 is taking place in the body in disease is the most important ques- 

 tion in medicine to-day. For its answer all the resources of science 

 must be brought to bear. The subject is rendered more compli- 

 cated by the fact that we are not dealing with a fixed but with a 

 variable quantity. Age, heredity, temperament, and social en- 

 vironment must all be considered. We cannot say, except with 

 wide limitations, what changes and variation in function will be 

 produced by the action of certain conditions. With the knowedge 

 of the effect of the drug on the healthy body, and the knowledge 

 of what changes are being produced in disease, and the effect of 

 which we wish to minimize, an intelligent experiment may be made. 

 Previous experimentation on animals should deprive the experi- 

 ment of all danger. 



Another change which has become apparent is the greater spe- 

 cialization not only in the exercise of the medical art, but in in- 

 vestigation. All increase of knowledge must bring with it special- 

 ization, for with the enlargement of the field comes the impossi- 

 bility of its control by one individual. Specialization has both 

 advantages and disadvantages. The advantages are, that inves- 

 tigations are more easily carried out by the simplification of the 

 questions and the familiarity with technical methods. Methods 

 of investigation have become so complicated that the necessary 

 skill can only be attained by the constant exercise of methods 

 only applicable in a very narrow field, and an investigator of ex- 

 ceptional ability in one line of work may be powerless in another. 

 A man may profitably devote his entire energies to the study of 

 the changes in nerve cells in disease, or may confine himself to the 

 study of a single species of bacteria. With the enormous increase 



