x CONTENTS 



CHAPTER XI. 



SULPHUR-BACTERIA : IRON-BACTERIA 



SECTION PAGE 



SULPHUR-BACTERIA : 



1. INTRODUCTION TO SULPHUR-BACTERIA - 144 



2. CLASSIFICATION OF THE SULPHUR-BACTERIA - 145 



Beggiatoa, Thiothrix, Thiophysa, and Purpur-bacteria. 



3. THE PHYSIOLOGY OF THE SULPHUR-BACTERIA 149 



IRON-BACTERIA : 



4. INTRODUCTION TO IRON-BACTERIA - - 151 



Crenothrix polyspora : Cladothrix dichotoma : Leptothrix ochracea. 

 Gallionella ferruginea : Clonothrix fusca : Spirophyllum ferru- 

 gineum. 



5. THE PHYSIOLOGY OF THE IRON-BACTERIA, - - - 160 



CHAPTER XII. 

 BACTERIA AND THE PRESERVATION OF FOOD-PRODUCTS 



1. INTRODUCTION 162 



2. FIRST METHOD OF FOOD-PRESERVATIONDESTRUCTION OF MICRO- 



ORGANISMS - - 164 



3. SECOND METHOD DRYING ... 165 



4. THIRD METHOD COOLING - - 167 



5. FOURTH METHOD USE OF CHEMICALS - 168 



6. PRESERVATION OF EGGS - 169 



CHAPTER XIII. 

 THE NITROGEN-BACTERIA 



1. INTRODUCTION - 171 



2. ACTIVITIES OF NITROGEN-BACTERIA WHEN FREE IN THE SOIL 172 



3. CONDITIONS OF NITROGEN-FIXATION - -.- - - 175 



4. NITROGEN-BACTERIA ACTING IN CONJUNCTION WITH LEGUMINOUS 



PLANTS -----..--.-- 177 



