XX CONTENTS 



PAGB 



Yellow Fever and Mosquitoes 241 



Ileniedittl Measures 242 



Plague 243 



Fleas and Plague 243 



Other Insects and Disease 244 



Mites, Ticks and Disease 244 



Government Sanitation 246 



Section 6. Death 



CHAPTER XXII 

 Death and the Duration of Life 



Nature of Death 249 



Hil>ernation or Winter Sleep 249 



Summer Sleep 260 



Effects of Freezing 260 



Length of Life 251 



Weismann's Theory 262 



Application of the Theory 252 



Old Age Modifications . . " 253 



Immediate Causes of Death 263 



Immortality of the I'nicoUular Organisms 264 



Death in Nlulticellular Organisms 256 



Death an Advantage to the Species 256 



Summary . . . 266 



Section 7. The R6le of Microorganisms 



CHAPTER XXIII 

 Decomposition 



The Disposal of Organic Wastes 269 



Decomposition 259 



Kinds of Decomposition 260 



The Agents of Decomposition 261 



The Principles of Decomposition 261 



Alcoholic Fermentation 262 



The Knzyms Concerned 263 



Commercial Uses of the Producta 263 



Acetic Fermentation 264 



The Souring of Milk 264 



The Hotting of Wood 265 



Commercial Fiber Production 265 



Decompo.sitif)n of Fats and Oils 266 



Decomposition of Nitrogenous Waste 266 



The Solid Nitrogenous Wastes 267 



Putrefication 267 



Putrefying Substances 267 



The Producta of Putrefaction 268 



