304 A MANUAL OF BACTERIOLOGY 



bear on such particular case all the evidence that it 

 is possible to obtain, and then interpreting this 

 evidence by the light of an extended experience, 

 that a sound judgment can be arrived at.' l 



From what has been said in the last three chap- 

 ters, it will be seen that we live in a world that is 

 teeming with life. The air, the soil, the waters of 



- ocean, river, and pond swarm with living microbes, 

 each more or less perfectly adapted to the conditions 

 of its existence. Many problems arise with regard 



f to this world of living things ; but suffice it to say 

 that almost every drop of water which evaporates 

 into the air carries with it germs, and there is no 

 reason to suppose that the germs perish. On the 

 contrary, there is much to lead us to believe that 

 the germs have far greater powers of resisting high 

 temperatures, desiccation, and other adverse con- 

 ditions than the fully developed microbes. We 

 may thus see how the air (and probably the soil) 

 comes to be laden with germs which, should they 

 fall into an appropriate infusion, or into water, may 

 give rise to the teeming life which we know to be 

 so soon developed in it. 



1 For further information see Fabre-Domerque's Manuel 

 Pratique d 1 Analyse Micrographique des Eaux (1890) ; Salazar 

 and Newman's Examen Quimico y Bacteriol6gico de las Aquas 

 Potables (1890) ; Giglioli's Fermenti e Microbi (1887) j Frank in 

 Zeitschrift fur Anal. Chemie, vol. xxx. p. 305 ; and Roux's 

 Precis d' Analyse Microbiologique des Eaux (1891). 



