17 
point of contact on its twelve to forty-eight hour journey to the con- 
sumer it receives additional bacteria. 
Milk holds a peculiar position among foodstuffs in that it is an 
excellent medium for the growth of many micro-organisms, both the 
ordinary saprophytic varieties and those pathogenic to man. These 
factors often produce in market milk an enormous bacterial content. 
Zakharbekoff found that in St. Petersburg examination of samples of 
milk as delivered to the houses showed the presence of from 10,200,000 
to 82,300,000 bacteria per cubic centimeter. Samples of market milk 
at Giessen have shown over 169,000,000 per cubic centimeter, New 
York City milk as high as 35,200,000, London milk 31,888,000. In 
Washington, examinations made at the Hygienic Laboratory of the 
Public Health and Marine Hospital Service during the summer of 
1906 showed a maximum of 307,800,000 and an average bacterial 
content of 22,134,289. Were milk transparent, this luxuriant growth 
would be evident to the naked eye, but because of its opacity such 
contamination occurs unnoticed. Fortunately, most of these organ- 
isms are saprophytes, but there are good reasons to believe that they 
may elaborate toxins, rendering milk dangerous as a food. 
It is evident, from a broad view of the subject, that a pure and 
wholesome milk supply is possible, and this volume contains all the 
necessary information to attain that end, as well as the existing stand- 
ards of purity to which it should conform. 
The three cardinal requirements, cleanliness^ cold^ and speedy trans- 
portation from the cow to the consumer must be observed, and the cow 
herself must be free from disease. For their observance, intelligence 
and care on the part of the dairyman and milk dealer are absolutely 
essential. 
The bearing of all these points upon the Avholesomeness of milk, 
its treatment when contaminated, and its use as an article of food, 
especially for infants, has been treated in detail by the various col- 
laborators. To ascertain how serious an indictment might be returned 
against milk as a carrier of disease, a compilation of epidemics pro- 
duced by this means has been made by Doctor Trask. Reports of 
500 epidemics have been abstracted in tabular form and appear in 
the text. These are only the few that have been reported and are 
accessible in the literature; how small a fraction of all cases this must 
be can only be surmised. 
As a result of large experience. Doctor Lumsden describes how the 
milk supply of cities becomes contaminated with typhoid bacilli, and 
the best epidemiological methods of determining the influence of milk 
as a factor in the propagation of typhoid fever. 
With a view to determining the presence or absence of tubercle 
bacilli in the market milk of Washington, Doctor Anderson examined 
45276 °— Bull. 56—12 2 
