BACTERIA, 

 YEASTS, AND MOLDS 



CHAPTER I 

 INTRODUCTION 



Bacteria, yeasts, and molds comprise a series of plants 

 commonly known as microorganisms, or more popularly as 

 microbes. It has for some time been recognized that 

 together they form a group of the utmost importance 

 not only to the physician but also to the agriculturist. 

 To-day it is beginning to be appreciated that their rela- 

 tion to the ordinary household, and hence to the house- 

 wife, is even more intimate than to the physician. We 

 are learning that many of the tasks of the housekeeper, 

 some of which may be more or less unpleasant, have their 

 foundation in bacteriology, and we are beginning to recog- 

 nize that these microorganisms constitute the foundation 

 of the demand for cleanliness so forcibly emphasized in 

 modern times. 



In the household microorganisms have an important 

 bearing in three directions : 



1. They are the cause of the decay and spoiling of foods 

 and many other products. 



2. They are sometimes of value in the preparation of 

 foods. 



3. They are the cause of contagious diseases. 



