v.] METHODS OF INOCULATION. 53 



Any given quantity of air for any length of time can be 

 passed through a series of such bottles, the one that receives 

 the air first being of course most contaminated. 



The bottles are after the experiment placed in the incubator, 

 if required, the outer end of their tubes being plugged with 

 cotton-wool. 



Miquel l has carefully described many ingenious methods 

 for the study of air-organisms. 



1 Les Organismes vivants de T Atmosphere, Paris, 1883. 



