PREFACE 



This is, we believe, the first occasion on which an attempt has been 

 made to deal in a systematic manner with the bacteriology of milk, 

 a subject which is year by year engrossing more of the attention 

 of the public and of the medical profession, on account of the 

 advances which have been made in preventive medicine in general 

 and bacteriology in particular. 



We commenced the serious work involved in writing the present 

 volume in 1899, and have thus spent, in available time at our 

 disposal, a period of some five years. The length of this period is 

 due in part to the ever-widening field which had to be covered, and 

 in part to unavoidable delays. Whilst this is to be regretted, there 

 is perhaps the advantage that no part of the work has been hastily 

 done. Yet for obvious reasons, the chief of which is the extremely 

 rapid growth of bacteriology, much of the work must be looked 

 upon as provisional only. The conditions affecting bacteria in 

 nature, the potentiality of bacteria in butter and cheese making, 

 and the species of bacteria belonging to milk are subjects still 

 requiring much more investigation than they have hitherto received. 

 The practical and applied aspect of the bacteriology of milk also 

 daims much fuller inquiry. For instance, comparatively little is 

 known of the relationship between disease in the cow and its trans- 

 mission to man by means of milk. Questions of preventive medicine 

 and of the control of the milk supply are also still open to revision. 

 We are under no illusion as to finality or completeness in this 

 volume. Few, probably, know better than ourselves of the 



