110 



SCIENCE 



[N. S. Vol. XLIV. No. 1126 



effect a given end. There exists, however, 

 a type of work in medicine with which the 

 public comes less in contact and which 

 concerns itself primarily with the funda- 

 mental understanding and elaboration of 

 those very means of prevention, relief and 

 cure which the physician applies. 



It would naturally occur to you that the 

 individual best fitted to discover means of 

 understanding and thereby of combating 

 disease, would be one fully conversant with 

 its manifestations and results through con- 

 stant and persistent contact with the sick. 

 Such, indeed, was the development of med- 

 ical science through many centuries. I 

 need only mention categorically a few of 

 the great discoveries that have been made 

 during the centuries by practising physi- 

 cians. Galen, in the second century of our 

 era, showed that control of the muscles de- 

 pends on integrity of the nerves that run 

 to them, by the simple experiment of cut- 

 ting certain of them in animals. In the six- 

 teenth century Versalius not only founded 

 the science of anatomy, but described the 

 mechanism of breathing and introduced 

 artificial respiration. Harvey in the seven- 

 teenth century experimentally demon- 

 strated the mode of circulation of the blood 

 in the animal body. Thomas Young laid 

 the foundation of physiological optics and 

 explained the principle of color differentia- 

 tion. Jenner showed conclusively that in- 

 oculation with cowpox will protect against 

 smallpox, and thereby laid the foundations 

 of vaccination as a preventive of many in- 

 fectious, parasitic diseases. Morton, in the 

 last century, discovered the principle of an- 

 esthesia, which has made surgery painless. 



You will notice that these examples con- 

 sist entirely of contributions which may be 

 regarded as fundamental principles rather 

 than adaptations of such principles, how- 

 ever practically valuable; in other words, 

 it is a list of discoveries rather than of in- 



ventions; on such basis I have omitted 

 Lister's great application of Pasteur's prin- 

 ciples of bacterial contamination in aseptic 

 and antiseptic surgery. You may further 

 observe that the contributors cited have 

 worked on experimental rather than purely 

 deductional lines ; I have not, for instance, 

 mentioned the important work of Auen- 

 brugger, who associated certain percussion 

 notes over the chest wall with diseased con- 

 ditions in the lungs and heart. I trust I 

 shall be able to convince you that essential 

 advance in medicine, as in other biological 

 sciences, lies in the development of prin- 

 ciples through inductive experimentation. 



In the popular mind and in popular fic- 

 tion it is still the well-known practitioner 

 who is the great contributor to medical sci- 

 ence. As a matter of fact to-day, and for 

 many years, the progress has been largely 

 due to a group of workers who are con- 

 cerned little, or often not at all, with the 

 care of the sick. Many major discoveries 

 have been made by men with no medical 

 training at all. I may simply mention 

 among the latter Pasteur and Metchnikoff, 

 whose contributions we shall later consider 

 in more detail. This differentiation in 

 medicine of a group of medical or even non- 

 medical men from medical practitioners, is 

 a specialization or division of labor that is 

 unknown to or misunderstood not only by 

 the general public, but even in the medical 

 profession itself. Its development is, how- 

 ever, quite logical and tending toward 

 greater efficiency. 



Progress in medical treatment a hundred 

 years ago, and to a great extent fifty years 

 ago, depended almost entirely on deductions 

 that were ingeniously made from personal 

 experience with the sick. The greater such 

 an experience was the greater and more 

 complete the series of facts obtained, the 

 more valuable the deductions from them. 

 Nothing approaching a complete series of 



