PART I. 



GENERAL NATURE OF MICROORGANISMS AND 

 THEIR ACTIVITIES. 



CHAPTER I. 

 THE GENERAL CHARACTERS OF MICROORGANISMS. 



MICROORGANISMS AND FARM LIFE. 



The successful farmer of to-morrow will be the one who most 

 skillfully regulates the growth of microorganisms. Though he 

 may not be conscious of it, much of the work that the farmer is 

 carrying on even now is, as we shall see, really directed toward the 

 control of germ life. In the consideration of the microorganisms 

 related to farm life we are concerned with three different types of 

 plants : Bacteria, Yeasts and Higher Fungi. Although the latter are 

 plants of considerable size, and hence hardly microorganisms, in many 

 respects they are related to the microscopic bacteria and yeasts, 

 and the functions of all three in farm life are so similar that all 

 must properly be considered together. The molds, being plants 

 of considerable size, have been known a long time, although only 

 recently has their relation to nature's processes been understood. 

 Yeasts were used, under the name of leaven, far back in history; 

 but it was not till 1680 that the Dutch microscopist, Leeuwenhoek, 

 showed with his microscope that yeast consists of minute globules; 

 and it was 150 years later when Schwann and Caignard-Latour 

 proved yeast to be a living plant. Leeuwenhoek was also first to 

 see bacteria, and studied them as early as 1695. His descriptions, 



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