PREFACE. 



The relation of milk to the public health and the means 

 employed to ensure a safe milk supply is a subject of varied 

 aspects. The proper control of the public milk supply requires 

 more or less of the services of the bacteriologist, the chemist, 

 the physician, the veterinarian, and the progressive dairyman. 

 The ordinary fund of technical knowledge possessed by any one 

 of these cla.sses is not sufficient for coping with the difficulties 

 encountered in carrying on efficient and comprehensive meas- 

 ures for milk and dairy inspection. Furthermore, knowledge 

 concerning the subject is being rapidly increased by contribu- 

 tions widely scattered in technical journals. 



The writer has attempted the difficult task of assembling the 

 essential facts for the information of the health officer and 

 others directly concerned in the crusade for better milk. The 

 class of individuals particularly addressed is such, that a gen- 

 eral knowledge of bacteriology is assumed to be yiossessed by 

 the reader. 



Each chapter is accompanied by a list of references bearing 

 on the subjects discussed. Throughout the text, numbers in 

 parenthesis, referring to the authorities given at the end of the 

 chapter, have been freely used. These references serve in some 

 cases to give statements greater weight than a mere unsup- 

 Ijorted personal opinion would have, and in all cases permit 

 those particularly interested to gain access readily to the details 

 concerning the points at issue. 



In the preparation of the book, the writer has become greatly 

 obligated to his colleague, Profe.ssor M. E. Jaffa, for writing 

 chapters X and XI. With reference to those chapters. Pro- 

 fessor Jaffa desires to have it stated that he has not attempted 

 to present the details of the more common methods employed 

 in the chemical examination of milk. This branch of milk 

 inspection is the most advanced and the methods are well estab- 

 lished. He has been content to indicate what should be done 



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