THE MICROSCOPE. 



in 



ATMOSPHERIC DUST AND GERMS. 



ATMOSPHERIC dust and germs have been the subject of a pro- 

 found study for the last few years at the Observatory of Mont- 

 souris, and the results obtained have recently been communicated 

 to the Faculty of Medicine, of Paris, by Mr. P. Miquel, chief of the 

 micrographic service of the former institution. 



Mr. Miquel did his collecting with an aeroscope (Fig. i) in- 



FIG. 1. 



vented by Mr. F. A. Pouchet. This apparatus consists of a cylinder 

 of small diameter connected with an aspirator, and provided with a 

 plate of glass covered with glycerine for receiving and retaining the 

 minute bodies carried along by the current of air. 



The number and variety of the spores that are disseminated by 

 the air is found to be immense (Figs. 2, 3 and 4). The spores of 

 Penicillium and the cells of Protococcus and Chlorococcus are almost 

 always present in great abundance Mr. Miquel applied himself at 



