xii CONTENTS. 



CHAPTER I. FOOD OF MICROORGANISMS 87 



The composition of the cell, Moisture, cell wall, cell contents. Amount of food re- 

 quired. Organic food materials, Non-nitrogenous food compounds, nitrogenous 

 food compounds. Mineral food. Oxygen. Additional remarks on microbial food, 

 Physiological groups, synthetic media. 



CHAPTER II. PRODUCTS OF METABOLISM 101 



The chemical equations of fermentations. Physiological variations. Products from 

 nitrogen-free compounds, Cellulose, starch, sugar, alcohols, organic acids, fats. Pro- 

 ducts from nitrogenous compounds, Protein bodies, ptomains, urea, uric acid.hip- 

 puric acid. Products from mineral compounds, Oxidations, reductions. Unknown 

 products of physiological significance, Pigments, aromatic substances, enzymes and 

 toxins. Rotation of elements in nature, Carbon cycle, nitrogen cycle, sulphur cycle, 

 phosphorus cycle. Physical products of metabolism, Production of heat, produc- 

 tion of light. 



CHAPTER III. MECHANISM OF METABOLISM 130 



General theory of metabolism, Fermentation (intra- and extra-cellular), katabo- 

 lism and anabolism. Intra- and extra-cellular fermentation. Decomposition of in- 

 soluble food, properties of enzymes, mechanism of fermentation. Classification of 

 enzymes, Hydrolytic enzymes (enzymes of carbohydrates, enzymes of fats, enzymes 

 of proteins), coagulating enzymes, zymases, oxidizing enzymes, reducing enzymes. 

 Additional remarks on the relation of cells and enzymes. Theory of katabolism. 

 Theory of anabolism, Interaction of anabolism and intra-cellular fermentation, 

 reversibility of enzymic action. 



DIVISION II. PHYSICAL INFLUENCES. 



CHAPTER I. MOISTURE 147 



Osmotic pressure. Plasmolysis, Salt and sugar solutions, colloidal solutions. Des- 

 iccation. 



CHAPTER II. INFLUENCE OF TEMPERATURE 153 



Optimum temperature. Minimum temperature. Maximum temperature. Bio- 

 logical significance of the cardinal points of temperature. End-point of fermentation. 

 Freezing. Thermal death-point. Resistance of spores. 



CHAPTER III. INFLUENCE OF LIGHT AND OTHER RAYS 162 



Phototaxis. X-rays. Radium rays. 



CHAPTER IV. INFLUENCE OF ELECTRICITY 166 



CHAPTER V. InFLUENCE OF PHYSICAL STRUCTURE OF THE MEDIUM 167 



CHAPTER VI. INFLUENCE OF MECHANICAL EFFECTS 168 



Pressure. Gravity. Agitation. 



DIVISION III. CHEMICAL INFLUENCES. 



CHAPTER I. STIMULATION OF GROWTH 171 



Chemotropism and chemotaxis. 



CHAPTER II. INHIBITION OF GROWTH . . 173 



Poisons, germicides, disinfectants, antiseptics, preservatives. Mode of action. Fac- 

 tors influencing disinfection. Classification of disinfectants. 



DIVISION IV. MUTUAL INFLUENCES. 

 SYMBIOSIS. METABIOSIS. ANTIBIOSIS . .181 



