156 The Theory of Atmospheric Germs. [April, 



these results are not the invariable teachings of experi- 

 ments. In case of certain putrescible fluids, and in 

 certain conditions, putrescence has not been prevented 

 by the means employed ; but it must be recollected that, 

 in all the instances quoted, parallel experiments were 

 carefully made. In the one case, wherein the air was 

 uncalcined or unfiltered, putrescence took place and 

 organisms appeared ; in the other, wherein the air was cal- 

 cined or filtered, there were no putrescence and no organi- 

 sation. The first step in the inquiry is the determination of 

 the substances besides the gaseous constituents which 

 are present in atmospheric air. The suspended matters are 

 proved to be — (1) A number of fine particles of inorganic 

 matter ; chloride of sodium derived from the sea is proved 

 by spectrum analysis to be present almost constantly ; fine 

 particles of the metals are present, especially in localities 

 where are prosecuted trades, wherein F 



they are manipulated. (2) A quan- „ 



tity of organic debris ; starch cells © ® 



and fragments of vegetable tissue are ° a ° a 



common ; cotton and wool fibres are « ;" ° ' • 

 found in certain localities besides %> ° & 



many kindred dry organic substances. • ° ° ° 



(3) Organic debris derived from the ^ O O 



animal body is also abundantly found, flw Q ° 



^0& %5fe /lift 



Epithelium cells have been frequently * ° °° " J> 



observed in ill-ventilated rooms ; qq o ° * 



Eiselt found pus cells in the air of an - ** Q ° 

 ophthalmic hospital; organic matter, a © 



moreover, is given Off from the lungS, Corpuscles obtained from atmo- 

 c 1 ' 1 ■ • 1 • i 1 1 spheric air, treated by (a) solution 



lor sulphuric acid is darkened, per- of potash, (&) aqueous solution of 

 manganate solution is decolourised iodine - (After Pasteur -) 

 and pure water rendered offensive by it. (4) Lastly, organised 

 bodies, spores of fungi, have been seen by a host of 

 observers. The appearance of organised bodies in ordinary 

 atmospheric air was first satisfactorily established by.Pasteur 

 (seefig. 1). Since his observation the microscopic examination 

 of air has been made in many ways by different observers, 

 and all have agreed as to the presence in it of sporules of 

 cryptogams, and of bodies possessed of vitality. 



The fact of the presence of organised bodies in the air 

 being to all intents and purposes uncontested, we have to 

 consider their possible relations in the causation of the 

 development of vital forms in putrescible solutions. On this 

 point there is wide difference of opinion. M. Pasteur, with 

 the Panspermatists, holds that they are the sources of all the 



