312 FRAGMENTS OF SCIENCE. 



Again, in order to utterly destroy all germs M. Pouchet 

 produced water from the combustion of hydrogen in air ; 

 but even in this water he found organisms. Had he seen, 

 however, as you have, the manner in which the air is clouded 

 with floating matter, would he have concluded that the 

 deportment of water which had been permitted to trickle 

 through such air could have the least influence in deciding 

 this great question ? I think not. Here is a quantity of 

 water produced and collected by allowing a hydrogen-flame 

 to play upon the polished bottom of a silver basin, in which 

 ice had been placed. This water is clear in the common 

 light ; but in the condensed electric beam it is seen to be 

 laden with particles, so thick-strewn and minute, as to pro- 

 duce a continuous cone of light. In passing through the 

 air the water loaded itself with this matter, and doubtless 

 became charged with incipient life. 



Let me now draw your attention to another experiment 

 of Pasteur. He prepared twenty-one flasks, each contain- 

 ing a decoction of yeast, filtered and clear. He boiled the 

 decoction, so as to destroy whatever germs it might contain, 

 and while the space above the liquid was filled with pure 

 steam he sealed his flasks with a blow-pipe. He opened ten 

 of them in the deep, damp caves of the Paris Observatory, 

 and eleven of them in the court-yard of the establishment. 

 Of the former, one only showed signs of life subsequently. 

 In nine out of the ten flasks no organisms of any kind 

 were developed. In all the others organisms speedily ap- 

 peared. 



Now here is an experiment conducted in Paris ; let us 

 see whether we cannot throw light upon it in London. I 

 place this large flask in the beam, and you see the luminous 

 track crossing it from side to side. The flask is filled with 

 the air of this room, charged with its germs and its dust, 

 and hence capable of illumination. But here is another 

 similar flask, which cuts a clear gap out of the beam. It is 



