216 INTERNAL MEDICINE 



logy, and exactly tested by improved methods of physiological 

 study, added greatly to the armamentarium of the physician for 

 the relief of symptoms. The power to combat disease specifically, 

 however, remained much as it was at the beginning of the century. 

 Mercury in syphilis, quinine in malarial fever, were the only spe- 

 cifics known to the medical world --and the action of these was 

 unexplained. 



The introduction by George Murray, less than fifteen years ago, of 

 the treatment of myxedema and allied conditions by extracts of the 

 thyroid gland, was a direct application of the results of physi- 

 ological observation to the treatment of disease. If this gave rise 

 to hopes of the possibility of obtaining like results from roughly 

 obtained extracts of other ductless glands, which have hardly been 

 fulfilled, yet the discovery was the first step toward the rational 

 scientific therapy to which we are beginning to look forward to-day. 



But a moment ago I spoke of the importance of the influence of the 

 discovery of the causal agents of the infectious diseases upon the 

 development of exact diagnostic and prophylactic methods. Great 

 and impressive as these have been, yet the studies which have fol- 

 lowed as to the manner in which these agents act upon the human 

 organism, and of the powers of resistance which the body exerts 

 against them, the investigation of the problems of immunity have 

 opened out a far wider field. The early studies of Metchnikoff and 

 Buchner and Nuttall were followed with rapidity by the epoch- 

 making work of Behring and Kitasato and Roux with regard to 

 tetanus and diphtheria. The diphtheria and tetanus antitoxins were 

 not chance discoveries of empirically determined virtue, but true 

 specific, therapeutic agents, the results of experiment scientifically 

 planned and carefully prosecuted. Widespread investigations of the 

 various phases of immunity, bacterial and cytotoxic, have given us 

 in a few short years a mass of physiological knowledge, the full 

 import of which is scarcely yet to be comprehended. Few things in 

 modern medicine are more impressive than a survey of the work of 

 the last twelve years done under the inspiration of Ehrlich. 



Beside the antitoxins of diphtheria and tetanus and the power of 

 producing a greater or less degree of immunity, as has already been 

 mentioned, by preventive inoculations against cholera, plague, and 

 typhoid fever, we have come to possess a bactericidal serum of a 

 certain value in combating the actual disease, plague, while the 

 favorable influence of Shiga's anti-dysenteric serum seems to be un- 

 doubted. There is much reason to hope that the recently promised 

 anti-crotalus serum of Noguchi as well as the anti-cobra serum of Cal- 

 mette may prove to be real boons to humanity. But it is not alone 

 in the production of specific anti-sera that the therapeutic value of 

 the modern studies of immunity lies. There are signs which justify 



