X Contents 



CHAPTER IV 



Pagea 



The Food Rbqtjirbmbnts of Bacteria 30-35 



The sources of carbon — The compounds of carbon in 

 bacteria — The source of nitrogen — Enzymes — Pigments 

 — Phosphorescence. 



CHAPTER V 



Conditions Affecting the Growth op Bacteria . . 36-44 



Temperature — Thermophile bacteria — Effect of cold — 

 Attenuated cultures — Moisture content of the culture 

 medium — Relation to oxygen — Action of sunlight — 

 Electric light — Influence of electric currents — Influence 

 of the concentration of the culture medium — The re- 

 action of the culture medium — Importance of reaction 

 of the soil. 



PART II 



Bacteria in Air and Water 45-103 



CHAPTER VI 



Bacteria in the Atmosphere 45-55 



Bacteria on dust particles — Determination of the bac- 

 teria in the air — Pasteur's method of determination — 

 Value of Pasteur's method — Quantitative methods. 

 Influence of locality — Bacteria in city air — Bacteria in 

 the air of the country. Influence of season climate, 

 and altitude — Bacteria in the air at different seasons of 

 the year — The influence of climate — The influence of 

 altitude — Bacteria and respiration. 



CHAPTER VII 



The Relation of Water to Health and Disease . . . 56-60 

 Ancient water-supplies — Relation of drinking-water and 

 disease discovered — Epidemics of cholera and typhoid 

 fever — Other sources of typhoid infection — Other dis- 

 eases arising from use of impure water. 



