210 BACTERIOLOGY 



been the outcome of the search for the utilitarian. Man's know- 

 ledge of the universe may be furthered in various ways. It is well 

 known that the work of Pasteur was particularly characterized by 

 applications to the problems of pure science of knowledge acquired 

 in the study of the practical. One thing plays into the hands of 

 another in wholly unexpected fashion. An attempt to improve the 

 quality of beer gives birth to the germ theory of fermentation, and 

 this in turn to the germ theory of disease; the chemistry of carbon 

 compounds leads to the discovery of the anilin dyes, and these same 

 anilin dyes have made possible the development of microchemic 

 technique and thrown open spacious avenues for experiment and 

 speculation; the attempt to obtain a standard for diphtheria anti- 

 toxin has resulted not only in the achievement of the immediate 

 practical end, but in the discovery of unexpected theoretic consid- 

 erations which have dominated the progress of an important branch 

 of scientific medicine during the last five years. It will not be a hope- 

 ful sign for the advancement of science when the worker in pure 

 science ceases to concern himself with the problems or avail himself 

 of the facilities afforded by the more eminently utilitarian aspects of 

 natural knowledge. 



In the quarter-century of its history, bacteriology has sustained 

 close and mutually advantageous relations with the science of 

 medicine. This has been the scene at once of its greatest endeavors 

 and of its greatest triumphs. To recount these would be superfluous. 

 There is hardly an hypothesis in scientific medicine that has not 

 been freshened and modified, hardly a procedure in practice that 

 has not been influenced by bacteriologic conceptions. The experi- 

 mental method in particular has been given new support and re- 

 ceived brilliant justification. Experimental pathology and experi- 

 mental pharmacology practically owe their existence to the methods 

 and example of bacteriology. The security afforded by aseptic 

 surgery has made possible physiologic exploits that could not other- 

 wise have been dreamed of, a pregnant illustration of the way in 

 which applied science may directly further the advance of pure 

 science. Conspicuous as these achievements of bacteriology have 

 been, it cannot be truly said that the field is exhausted. There is 

 hardly an infectious disease of known or unknown origin that does 

 not still harbor many obscurities. Some of the most difficult pro- 

 blems that medicine has to face are connected with the variation and 

 adaptation of pathogenic bacteria. The phenomena of immunity, 

 certainly among the most complicated and important that human 

 ingenuity has ever set itself to unravel, still await their full de- 

 scription and interpretation. The study of the ultramicroscopic, 

 or perhaps more correctly the filterable viruses, is being prosecuted 

 with great energy and in a sanguine spirit. The extension of bac- 



