122 THE DEATH-POINT OF BACTERIA 
’ 
other cases, however (as in many of those instances 
where urine or hay- or turnip-infusions have been 
employed), those who do not content themselves with 
a mere naked-eye inspection of the apparently pure 
fluids would find on microscopical examination of the 
sediment that such fluids were to a low degree self- 
fermentable—that they correspond, in fact, with group 
E of the last subclass;* whilst, in addition, my re- 
searches have shown that many of such fluids are 
capable of being rendered self-fermentable to a 
marked degree, if, instead of subjecting them to 
contact with calcined air or variously filtered air, its 
reflux after ebullition is altogether prevented by her- 
metically sealing the neck of the flask during ebullition. 
Operating in this way, I have repeatedly found that 
fluids freed from the pressure of air and from its in- 
fluence altogether, become to a marked extent self- 
fermentable, although the same fluids exposed to 
filtered or calcined air under ordinary atmospheric 
pressure remain unaltered and barren, or at most 
exhibit the very low degree of fermentability referred 
* Other fluids richer in organic matter or otherwise more favourably 
endowed, instead of presenting this low degree of self-fermentability, are 
notably prone to undergo change when we attempt to preserve them in 
the manner described, although such modes of preparation do suffice for 
preserving so many fluids, This has been fully admitted by Schroeder 
and Dusch, Schwann, Pasteur, and others, 
