Juke 16, 1905.] 



SCIENCE. 



907 



Pasteur, revealed to the world the basis of 

 true cleanliness in asepsis, and in 1876, 

 bacteriology became firmly established as 

 a science by Koch's studies on anthrax. 

 The decade from 1880 to 1890 may be 

 called the golden age of etiology, for in 

 these years were discovered the hitherto un- 

 known parasitic microbes of typhoid fever, 

 tuberculosis, malaria, Asiatic cholera, diph- 

 theria and tetanus. The last decade of a 

 century which has well been called 'the 

 wonderful,' witnessed the discovery of 

 antitoxins by Behring and the beginnings 

 of serum therapy. The list is long, and I 

 have not mentioned nearly all of the dis- 

 coveries of capital importance, but because 

 of these and their fruits, I am in the habit 

 of saying to my students that with the 

 single exception of the changes effected by 

 the acceptance of the theory of organic 

 evolution, there has been no modification of 

 human opinion within the nineteenth cen- 

 tury more wonderful, or more profoundly 

 affecting the general conduct of human 

 life, than that in our attitude toward the 

 nature, the causation and the prevention 

 of disease — that is to say, toward public 

 health science. 



No mere outline like this of the history 

 of public health science can possibly serve 

 to show how, like other applied sciences, 

 this one has not grown as a branch grows 

 from a tree, namely, from a large stem or 

 stock of knowledge, tapering out into thin 

 air, and with its latest growth its least and 

 weakest. That common simile in which 

 the various divisions of science are repre- 

 sented as branches of the tree of knowl- 

 edge, is a grotesque survival of a time when 

 neither trees nor science were understood. 

 No simile is perfect or even approximately 

 correct, but one better than the tree and 

 its branches for the origin and relation- 

 ships of any inductive science is that of a 

 river, rising from various and often ob- 



scure sources, groAving in size and impor- 

 tance as it proceeds both from the springs 

 within its own bed and by the entrance 

 and contributions of tributary streams, 

 and finally pouring its substance into 

 the mighty ocean of accumulated human 

 knowledge. 



Up to the time of the establishment of 

 the registration of vital statistics in Eng- 

 land, in 1839, the stream of public health 

 science, although full of promise, was only 

 a slender thread, but when the results of 

 registration were fully enlisted in its 

 service it visibly widened and deepened. 

 Epidemiology, as has been said, had the 

 honor of giving birth to the science in 

 1767, and it added to its offspring a rich 

 endowment w^hen, in 1854, Dr. John Snow 

 proved that the water of the Broad Street 

 well in London had caused an epidemic, 

 in which more than six hundred persons 

 died of Asiatic cholera. The stream of 

 public health science was still further en- 

 larged and quickened by the revelation in 

 and after the sixties of the simple causes 

 of numerous epidemics of trichinosis and 

 of typhoid fever, the latter sometimes 

 through milk. There was an extraordi- 

 nary popular awakening in England to 

 the importance of sanitation and public 

 health measures in the middle of the nine- 

 teenth century, but we look for some time 

 in vain for any marked inosculation be- 

 tween public health science and other sci- 

 ences, such as physics, chemistry, micro- 

 scopy, bacteriology, climatology, engineer- 

 ing or education. We have, to be sure, 

 minor contributions from the mieroscopists, 

 such, for example, as that from Dr. Has- 

 sall, who, in 1850, made a careful micro- 

 scopical examination of the water supply 

 of London and showed the presence in the 

 public drinking water of muscle fibers, 

 intestinal parasites and other materials, 

 plainly derived from sewage ; but it was 



