348 Professor Tyndall on Germs. Fiat 
days. No matter where the infusions were placed, they were 
infallibly smitten. The number of the tubes containing the in- 
fusions was multiplied till it reached six hundred, but not one of 
them escaped infection. 
“ In no single instance, on the other hand, did the air, which 
had been proved moteless by the searching beam, show itself to 
possess the least power of producing bacterial life or the associ- 
ated phenomena of putrefaction. The power of developing such 
life in atmospheric air, and the power of scattering light, are 
thus proved to be indissolubly united. 
“ The sole condition necessary to cause these Jong-dormant 
infusions to swarm with active life is the access of the floating 
matter of the air. After having remained for four months as 
pellucid as distilled water, the opening of the back door of the 
protecting case, and the consequent admission of the mote-laden 
air, suffice in three days to render the infusions putrid and full 
of Bie.. $ 
“ From the irregular manner in which the tubes are attacked, 
we may infer that, as regards quantity, the distribution of the 
germs in the air is not uniform. The singling out, moreover, 
of one tube of the hundred by the particular bacteria that develop 
a green pigment, shows that, as regards quality, the distribution 
is not uniform. The same absence of uniformity was manifested 
in the struggle for existence between the bacteria and the peni- 
cillium. In some tubes the former were triumphant ; in other 
tubes of the same infusion the latter was triumphant. It would 
seem also as if a want of uniformity as regards vital vigor pre- 
vailed. With the self-same infusion the motions of the bacteria 
in some tubes were exceedingly languid, while in other tubes the 
motions resembled a rain of projectiles, being so rapid and vio- 
lent as to be followed with difficulty by the eye. Reflecting on 
the whole of this, the author concludes that the germs float 
through the atmosphere in groups or clouds, with spaces more 
sparsely filled between them. The touching of a nutritive fluid 
by a bacterial cloud would naturally have a different effect from 
the touching of it by the interspace between two clouds. But as, 
in the case of a mottled sky, the various portions of the land- 
Scape are successively visited by shade, so, in the long run, are 
the various tubes of our tray touched by the bacterial clouds, 
the final fertilization or infection of them all being the conse- 
quence. The author connects these results with the experiments 
e EB A E A tee Miers O aa TS 
PaE t i Rar an oc A em fee th EA 
