128 THE DEATH-POINT OF BACTERIA 
sive. It has been unmistakably proved that such 
organisms and their imaginary germs are either 
actually or potentially killed by a brief exposure to the 
temperature of 140° F. when in the moist state; and 
it had also been previously established that they are 
invariably killed by desiccation even at much lower 
temperatures.* 
But if living germs do not come from the air to 
contaminate the previously boiled fluids, and if it is 
not possible for any of them to have escaped the des- 
tructive influence of heat in the boiling fluid or on 
the walls of the vessel in which the fluid is contained, 
what can be the mode of origin of the swarms of 
living things which so rapidly and invariably appear 
in such infusions when contained in open flasks, and 
which so frequently appear when the infusions are 
contained in flasks whose necks are closed against 
* See the experiments and conclusions of Dr. Burdon Sanderson in 
Thirteenth Report of Med. Officer of Privy Council, p. 61. This fact 
of the inability of these organisms and their germs to resist desiccation 
shows the futility of some objections which have been from time to time 
raised by those who thought that Bacteria, Vibriones, and their germs 
might resist the destructive influence of heat (by adhesion to the glass 
above the level of the fluid, or even in the fluid itself), just as dried and 
very thick-coated seeds have been known to do. Dry heat would seem 
to be even more fatal to such organisms and their germs than a moist 
heat of the same degree, owing to their extreme inability to resist 
desiccation : if they become dry they are killed at a temperature of 
about 104° F., whilst if they remain moist they succumb, as we have 
seen, to a temperature of 140° F. 
