viii PREFACE 



immensity of the field which he must study who would learn even 

 the elementary principles controlling the life and action of micro- 

 organisms in milk. Our aim has been to systematise the bacterio- 

 logical study of milk rather than incorporate every known or tested 

 fact concerning the subject. For those who desire to follow the 

 matter more minutely we commend the references in the footnotes 

 and the Bibliographia Lactaria. 



The chapters on technique have been written in more detail 

 than is perhaps usual in books of this nature. But, anyone who 

 has worked at practical bacteriology is aware how necessary it still 

 is to describe, with minuteness, the different steps taken. We 

 have also added a chapter on the examination of air and water as 

 they affect the milk supply. 



The relationship existing between milk-borne disease and the 

 bacteriology of milk is, of course, intimate and essential, and, 

 therefore, several chapters have been devoted to pathogenic 

 bacteria in milk and milk-borne epidemics. This has naturally 

 led on to the questions of prevention and control. Whilst we 

 recognise that these latter questions have no direct relation to the 

 bacteriology of milk, the indirect relation is so strong, and a wise 

 control depends so entirely upon a knowledge of the bacteriology 

 of milk, that we have decided on the whole that it is most con- 

 venient to all concerned to bind up the chapters on the academical 

 and practical sides of the subject in one volume. 



Whilst the authors share jointly the views expressed throughout 

 the book, it should be understood that to Dr Newman has fallen 

 the writing of the chapters on the pathogenic organisms in milk 

 and the control of the milk supply. The whole of the laboratory 

 work necessary in the production of the book has been done in Mr 

 Swithinbank's laboratories at Denham, and he is also responsible 

 for the photographs, with the exception of the micro-photographs, 

 which were taken from our own preparations by Dr Harold Spitta 

 of the Bacteriological Department of St George's Hospital. 



We owe our thanks to Dr Mervyn H. Gordon of the Bacterio- 

 logical Laboratories of St Bartholomew's Hospital for the four 



