96 BACTERIOLOGICAL METHODS 



organisms, as will be explained later. It is also evident that 

 the isolation or the identification of the colon bacillus in a mixed 

 contamination as all sewage-contaminated substances are, is 

 not as simple a matter as might appear on first consideration. 

 However, the presumptive tests for the presence of the colon 

 bacillus in definite quantites of the food materials or liquids used 

 with, or associated with, certain food materials, is almost uni- 

 versally accepted as evidence of the dangerous contamination 

 with sewage. It is, however, quite clear that health officers 

 should not adopt hard and fast rules or standards for the con- 

 demnation of foods because of such evidence of sewage con- 

 tamination. Very naturally, the standard for water supplies 

 will not apply to oysters and shellfish generally and the standard 

 for shellfish will not be practically applicable to mineral waters, 

 etc. With substances of which the standard or quality is quite 

 generally based upon a numerical count, as for example milk, 

 the presumptive colon bacillus test need not be applied, unless 

 it is to be carried out as giving corroborative evidence of the 

 sewage contamination. 



One of the first important duties of the food and drugs bac- 

 teriologists will be for them to get together and agree upon uni- 

 form methods and to decide upon the kinds of bacteriological 

 examination under the pure food and drugs act to which the 

 quantitative as well as the qualitative (presumptive colon bacillus 

 test) determinations are applicable, in harmony with our present 

 knowledge of food bacteriology. The working laboratory methods 

 adopted must be practicable and must be carried out primarily 

 as a better protection of the physical well-being of the consumer, 

 incidentally also safeguarding the business interests of the con- 

 scientious manufacturers. The following suggestions are in- 

 tended to indicate along what lines the practical qualitative work 

 may be done and also to outline certain research work which should 

 be carried on in order to develop the working methods to greater 

 perfection and to add such new methods as may prove useful. 



