CHAPTER I. 



STRUCTURE, GROWTH AND DISTRIBUTION. 



Relation of bacteriology to dairying. The arts which 

 have been developed by mankind have been the out- 

 growth of experience. Man first learned by doing, how 

 to perform these various activities, and a scientific 

 knowledge of the underlying principles which govern 

 these processes was later developed. 



The art of dairying has been practiced from time im- 

 memorial, but a correct understanding of the funda- 

 mental principles on which the practice of dairying rests 

 is of recent origin. In working out these principles, 

 chemistry has been of great service, but in later years, 

 bacteriology has also been most successfully applied to 

 the problems of modern dairying. Indeed, it may be 

 said that the science of dairying, as related to the prob- 

 lems of dairy manufacture is, in large degree, depend- 

 ent upon an understanding of bacteriological principles. 

 It is therefore essential that the student of dairying, 

 even though he is concerned in large measure with the 

 practical aspects of the subject, should acquire as com- 

 plete an understanding of these principles as possible. 



While bacteriology is concerned primarily with the 

 activities of those microscopic forms of plant life known 

 as the bacteria, yet the general principles governing the 

 life of this particular class of organisms are sufficiently 

 similar to those governing the molds and other types of 

 microscopic life that affect milk and its products to make 



