34 BACTERIOLOGICAL METHODS 



the quantitative estimation of the microbic contamination of 

 certain food supplies, and still more recently the laboratory 

 division of the U. S. PubHc Health Service has done much efhcient 

 work on the standardization of disinfectants. We must also 

 mention the work on milk, meat inspection, etc., by the Bureau 

 of Animal Industry and the work on sanitation and related sub- 

 jects by the U. S. Public Health Service, not forgetting to men- 

 tion the vast amount of routine analyses in state and municipal 

 health laboratories and the sporadic research work in the bio- 

 logical and bacteriological laboratories of our colleges and uni- 

 versities and the individual investigations of food and drug 

 contamination on the part of a few of the more enterprising state 

 and municipal health officers. Very recently the sanitary study 

 of mineral waters has received a great deal of attention on the 

 part of individual workers. The Committee of the Laboratory 

 Section of the American Public Health Association has prepared 

 a report covering the general conclusions regarding some of the 

 methods of analysis. 



The purely microscopical examination of food substances and 

 of drugs, with reference to contamination by mold, yeast and 

 bacteria, should be a part of the work of the bacteriologist rather 

 than that of the chemist. Therefore, for the sake of completeness, 

 this phase of the subject is included in the present report. We 

 shall now proceed with the discussion of the bacteriological method 

 applicable in food and drugs laboratories, giving only the essential 

 details, however adding certain suggestions intended as a guide 

 for further investigation with a view to the improvement of the 

 present working methods. Detailed description of apparatus and 

 of technique will be given only when thought necessary. 



For all practical purposes, the examination of foods and drugs 

 for the presence of biologic contamination (inclusive of bacteria, 

 yeasts, molds, protozoa, ova and larvae of higher animal parasites, 

 etc., etc.) is either made directly or indirectly. That is, the sub- 

 stance is either placed on a slide or counting apparatus and the 



