July 6, 1906.] 



SCIENCE. 



11 



the discovery of the propagation of this 

 class of disease through an insect host. 



The deepest impress which has been 

 made upon the average death rate of cities 

 has been in the reduction of infant mortal- 

 ity through a better understanding of its 

 causes. The Rockefeller Institute, by the 

 investigations which it has supported of 

 the questions of clean milk and of the 

 causes of the summer diarrhoeas of infants, 

 has already made important contributions 

 to this subject, which have borne good fruit 

 in this city and elsewhere. 



No outcome of the modern science of 

 bacteriology has made a more profound im- 

 pression upon the medical profession and 

 the public, or comes into closer relation to 

 medical practise than Behring's discovery 

 of the treatment of diphtheria by antitoxic 

 serum, whereby in the last twelve years the 

 mortality from this disease has been re- 

 duced to nearly one fifth of the former 

 rate. 



The most stupendous task to which the 

 medical profession has ever put its hands 

 is the crusade against tuberculosis, whose 

 preeminence as the leading cause of death 

 in all communities is already threatened. 

 Sufficient knowledge of the causation and 

 mode of spread of this disease has been 

 gained within the last quarter of a century, 

 to bring within the possible bounds of real- 

 ization the hopes of even the most en- 

 thusiastic, but it will require a long time, 

 much patience and a combination of all 

 the forces of society, medical, legislative, 

 educational, philanthropic, sociological, to 

 attain this goal. 



Time forbids further rehearsal, even 

 in this meager and fragmentary fashion, 

 of the victories of preventive medicine. 

 Enough has been said to make clear that 

 man's power over disease has been greatly 

 increased in these latter days. But great 

 and rapid as the progress has been, it is 

 -small in comparison with what remains to 



be done. The new fields which have been 

 opened have been explored only in rela- 

 tively small part. There still remain im- 

 portant infectious diseases whose secrets 

 have not been unlocked. Even with some 

 whose causative agents are known, notably 

 pneumonia and other acute respiratory 

 affections, and epidemic meningitis, very 

 little has yet been achieved by way of pre- 

 vention. The domain of artificial im- 

 munity and of the treatment of infections 

 by specific sera and vaccines, so auspi- 

 ciously opened by Pasteur and by Behring, 

 is still full of difficult problems, the solu- 

 tion of which may be of immense service 

 in the warfare against disease. Of the 

 cause of cancer and other malignant tu- 

 mors nothing is known, although many 

 workers with considerable resources at their 

 disposal are engaged in its study. With 

 the change in the incidence of disease, due 

 at least in large part to the repression of 

 the infections of early life, increased im- 

 portance attaches to the study of the circu- 

 latory, renal and nervous diseases of later 

 life, of whose underlying causes we are 

 very imperfectly informed. There are and 

 will arise medical problems enough of 

 supreme importance to inspire workers for 

 generations to come and to make demands 

 upon all available resources. 



In directing attention, as I have done, 

 to some of the practical results of scientific 

 discovery in medicine, and in indicating 

 certain of the important problems awaiting 

 solution, there is always the danger of giv- 

 ing to those unfamiliar with the methods 

 and history of such discovery a false im- 

 pression of the way in which progress in 

 scientific knowledge has been secured and 

 is to be expected. The final victory is 

 rarely the result of an immediate and direct 

 onslaught upon the position ultimately se- 

 cured. The advance has been by many 

 and devious and gradual steps, leading 

 often, it might appear, in quite different 



