280 THE EVOLUTION OF LIFE 
recorded, this seems only capable of receiving one 
interpretation. All the old objections to the notion 
of their de zovo origin have again been fairly met. 
The organisms found have undoubtedly been living, 
and they have occurred in tubes which had been 
Hambés, before they and their contents were sub- 
mitted to lethal temperatures. 
It is now generally admitted, as we have seen, 
that all micro-organisms, in their full-grown con- 
dition, are killed by the briefest exposure in fluids 
to 100° C.—to say nothing of lower temperatures. 
The spores of Bacilli are recognised as the only 
products of micro-organisms capable of resisting 
such an exposure. Yet, as we have found, various 
other forms that are admitted to be killed at roo’ C. 
can, and do, constantly appear within closed vessels 
which have been heated to this temperature for ten 
to twenty minutes. This applies, among other less 
known forms, to Bacteria, Vibriones, Micrococci, 
Streptococci, Torule, and other germs of Moulds. 
When these organisms appear under such conditions, 
therefore, we can only conclude that they must 
have been evolved de novo. 
In regard to ordinary Bacilli, the position, as we 
have seen, is different. These particular forms 
possess “spores,” which, at all events after they 
have undergone desiccation, are capable of resisting 
a higher degree of heat. The extent of their powers 
of resistance has been differently estimated, but after 
prolonged researches in the Pasteur Institute, the 
point was formerly fixed by the master himself at 
110 C., and later, after two years’ work, could only 

