THE BACTERIOLOGIC EXAMINATION OF MILK 411 



that initial contamination with pathogenic bacteria is, as a rule, 

 relatively small, so that, after the milk has been suitably diluted 

 for making the bacteria count, pathogenic bacteria are so scarce 

 that they are almost universally overlooked. For these reasons 

 attempts to isolate disease germs from milk are rarely made by 

 bacteriologists, although, if a rapid method of isolation were 

 known, it would be of distinct value, as milk-borne epidemics 

 could be more promptly terminated. 



It is true that after an epidemic has broken out we have 

 more rapid means than the determination of types of bacteria to 

 find whether a milk-supply is guilty. The evidence obtainable 

 by these means is usually very convincing, and the finding of a 

 specific disease germ rarely adds materially to the evidence. 

 Therefore, at the present state of bacteriologic technic evidence 

 of the infectiousness of milk is circumstantial and depends upon 

 the fact that the epidemic follows in the wake of a certain supply, 

 and that when the incriminated supply is removed from the 

 market the epidemic terminates. 



When extraordinarily large numbers of bacteria are present in 

 milk and a great variety represented, it is frequently argued that 

 the same carelessness or ignorance which permits the admission 

 of many micro-organisms may be the cause of the entrance of 

 pathogenic varieties. This is the chief reason for the establish- 

 ment of bacterial standards; but are standards really of as great 

 value as some sanitarians have assumed? Jordan says, "The 

 numbers of bacteria in milk have little meaning unless the sani- 

 tary history of the milk is known." In other words, the keynote 

 of the production of sanitary milk is to be found in inspection of 

 the health of the cows; the health of employees; the cleanliness in 

 the care of the milk in all stages, and a suitable temperature dur- 

 ing transportation. It is true that the inspector has no better 

 guide for his work than the bacterial examination which should 

 extend beyond market milk to the product in earlier stages. But 

 it is obvious that milk with large numbers of harmless bacteria 

 has little influence on health, while one with a small number of 

 pathogenic germs is injurious. 



However, if the producer is taught to furnish a milk with low 

 bacterial content there is a distinct moral gain. The greater the 

 care and intelligence exercised in milk production, the smaller, 

 probably, are the chances of infectious material entering. This 

 has been abundantly shown by the influence certified milk has 

 exerted on milk production in general. 



Some dealers have gained much credit in public opinion by 

 advertising their milk as being of low bacterial content. From 

 an esthetic viewpoint such milk is highly commendable and 



