INTRODUCTION 33 



investigation of the biological factors influencing the quality of 

 food and drugs and the significance of pure food and drugs in 

 the maintenance of the public health and the physical well-being 

 of the human race, as against the pernicious effects of contami- 

 nated foods and drugs. 



The question for first consideration is what bacteriological 

 methods are necessary and practicably applicable in testing 

 foods and drugs? This phase of the subject is comparatively 

 new and accordingly there are but few food and drugs bacteri- 

 ologists who have had any considerable general range of ex- 

 perience, and as a consequence there are comparatively few 

 methods fully worked out. Most of the bacteriological in- 

 vestigations and researches pertaining to foods have been along 

 special lines, and indeed much valuable information and useful 

 data have been brought together. Within the last lo years the 

 work on the sanitary examination of milk and of water supplies 

 has become monumental in volume as well as in importance. 

 Numerous methods have been tried, some to be entirely abandoned 

 after being for a time heralded as the final word in determining 

 the potability of water supplies. The same may be said of the 

 development of the bacteriological examinations of milk supphes. 



Quite recently bacteriologists have given considerable atten- 

 tion to the sanitary examination of shellfish, more especially 

 with reference to sewage contamination. In this investigation 

 American bacteriologists have taken the lead. European bac- 

 teriologists have done an enormous amount of work in the ex- 

 amination of sewage and of sewage disposal, to say nothing of 

 the classical researches on yeasts and on fermentation in general. 

 However, the general bacteriology of foods and of drugs is as yet 

 an unexploited field. It is true, the Bureau of Chemistry of 

 the Department of Agriculture has, within recent years (since 

 1906), done considerable work on the sewage contamination of 

 oysters and other shellfish (Bulletin No. 136, Bureau of Chemistry. 

 U. S. Department of Agriculture, by George W. Stiles) and in 



