THE MICROBES OF THE AIR 



263 



interesting and attractive. The investigations of 

 Burdon Sanderson, Tyndall, Lister, and Lankester 

 have all thrown considerable light upon the condi- 

 tions of life of these lower organisms ; but Pasteur 

 was the first investigator who made a systematic 



Fio. 51. MIQUEL AND DE FREUDENREICH'S FILTER. 



A, Filter-tube (A, enlargement of same, with cap at d). 



B, Aspirator. C, Gasometer. 



study of the presence and distribution of microbes 

 in the atmosphere. 



It was not, however, until 1879 that Drs. Miquel 



