CONTENTS 



XI 



CHAPTER PAGE 



XVIII. FERMENTATION OF POLYSACCHARIDES AND FATS THE 



GUMS HEMICELLULOSES AND CELLULOSES 220 



Distribution Fermentation Fermentation of Pecgin, the 

 process of retting Fermentation of starch and inulin 

 Fermentation of fatty acids and glycerin. 



XIX. DECOMPOSITION OP ORGANIC NITROGENUS COMPOUNDS 



RIPENING OF CHEESE AND OF MEAT 228 



Types of organisms The anaerobic, putrefactive bac- 

 teria Aerobic, proteolytic bacteria Proteolytic 

 changes in foods The ripening of cheese Types of 

 cheeses Ripening of meat. 



XX. BACTERIA OF THE SOIL THE CYCLES OF THE ELEMENTS . . . 238 

 Importance of bacteria in the soil Abundance and dis- 

 tribution of bacteria in the soil Cycles of the elements 

 The cycle of nitrogen in nature with special reference to 

 the soil Outline Proteolysis, ammonification or de- 

 aminization Nitrification Assimilation of nitrogen by 

 plants Denitrification Nitrogen fixation The cycle 

 of carbon Production of carbon dioxide in soil by mi- 

 croorganisms The decomposition of insoluble carbohy- 

 drates in the carbonaceous matter in the soil The 

 cycle of phosphorus The cycle of sulphur Organ- 

 isms oxidizing hydrogen sulphide and free sulphur Or- 

 ganisms reducing sulphates to sulphides The cycle of 

 iron. 



SECTION V 

 MICROORGANISMS AND DISEASE 



XXI. DISEASE, INFECTION, AND RESISTANCE 273 



DiseaseContagious and noncontagious diseases 

 Factors predisposing to disease Heredity and dis- 

 ease Immunity Exhaustion theory of immunity 

 Noxious retention theory Pythogenic theory of 

 disease Ehrlich's Humoral Theory of Immunity 

 Metschnikoff's Theory of Phagocytosis Kinds of 

 immunity Factors which determine immunity 

 Antigens and their corresponding antibodies Toxins 

 and antitoxins Sources of toxins Origin of anti- 

 toxin Manufacture of diphtheria antitoxin Prep- 

 aration and standardization of toxins Injection 

 of the toxin Standardization of antitoxin serum 

 Preparation and utilization of other antitoxins 

 Agglutinins and pricipitins Colloidal solutions and 

 suspensions Agglutination Protein Precipitation 



