PREFACE TO THIRD EDITION 



The first edition of the Standard 

 Methods for Milk Examination was 

 prepared by a committee consisting of 

 F. H. Slack, Chairman, W. H. Park, 

 B. H. Stone, H. L. Russell, C. E. 

 Marshall, and F. C. Harrison, and was 

 issued by the American Public Health 

 Association in 1910. A second edition 

 of this report was prepared in 1916 by 

 a committee consisting of M. P. Rav- 

 enel, Chairman, J. A. Anderson, H. W. 

 Conn, W. H. Park and R. S. Breed with 

 B. H. Stone and W. R. Stokes as 

 adjunct members. This committee 

 worked in cooperation with committees 

 from the Society of American Bac- 

 teriologists and of the American Dairy 

 Science Association. 



The present third edition report has 

 been prepared by a committee con- 

 sisting of W. H. Park, Chairman, 

 M. P. Ravenel, R. S. Breed, J. A. 

 Anderson and H. A. Harding with 

 B. H. Stone and W. R. Stokes as 

 adjunct members. This committee has 

 sought and obtained the cooperation 

 of still other associations interested in 

 the sanitary control of milk in an 

 effort to make the report truly rep- 

 resentative of American laboratory 

 workers. 



A summary of the more important 

 changes from the second edition follows: 



1. The scope of the report has been 

 broadened to cover the sediment test 

 and the examination of milk for the 

 presence of long chain streptococci. 



2. A summary of required pro- 

 cedures is given at the end of the 

 report. 



3. Encouragement is given for fur- 

 ther investigation of promising new 

 laboratory methods. 



4. Official recognition is given to 

 microscopic counts made directly from 

 unpasteurized milk. 



5. Methods for determining the 

 H-ion concentration of agar media are 

 given. 



6. It is recommended that the 

 practice of speaking of agar plate 

 counts as showing the number of 

 "bacteria" per cc. be discontinued 

 and that a more accurate form be used. 

 7. It is insisted that punitive actions 

 should be based upon the average 

 results from a series of samples, and 

 that the routine counts should be 

 verified by suitable procedures when 

 actions based on their use are likely 

 to be questioned. 



