nt place in the curriculum of almost every Dairy
School. An exposition of its principles is now recognized as an integral
part of dairy science, for modern dairy practice is rapidly adopting the
methods that have been developed as the result of bacteriological study.
The rapid development of the subject has necessitated a frequent
revision of this work, and it is gratifying to the writer that the
attempt which has been made to keep these Outlines abreast of
bacteriological advance has been appreciated by students of dairying.

While the text is prepared more especially for the practical dairy
operator who wishes to understand the principles and reasons underlying
his art, numerous references to original investigations have been added
to aid the dairy investigator who wishes to work up the subject more
thoroughly.

My acknowledgments are due to the following for the loan of
illustrations: Wisconsin Agricultural Experiment Station; Creamery
Package Mfg. Co., Chicago, Ill.; and A. H. Reid, Philadelphia, Pa.

H. L. Russell.
University of Wisconsin.

CONTENTS.

CHAPTER I. Structure of the bacteria and conditions governing
their development and distribution 1

CHAPTER II. Methods of studying bacteria 13

CHAPTER III. Contamination of milk 19

CHAPTER IV. Fermentations in milk and their treatment 62

CHAPTER V. Relation of disease-bacteria to milk 82

Diseases transmissible from animal to man
through diseased milk 84

Diseases transmissible to man through infection
of milk after withdrawal 94

CHAPTER VI. Preservation of milk for commercial purposes 102

CHAPTER VII. Bacteria and butter making 134

Bacterial defects in butter 156

CHAPTER VIII. Bacteria in cheese 160

Influence Of bacteria in normal cheese processes 160

Influence of bacteria in abnormal cheese processes 182

CHAPTER I.

STRUCTURE OF THE BACTERIA AND CONDITIONS GOVERNING THEIR DEVELOPMENT AND
DISTRIBUTION.

Before one can gain any intelligent conception of the manner in which
bacteria affect dairying, it is first necessary to know something of th