216 THE EVOLUTION OF LIFE 
time, would seem to have been a phenomenon of 
the rarest occurrence; germs capable of resisting a 
short boiling must have been almost, if not quite, 
unknown. 
But no magician with his wand ever wrought a 
more complete change than did Professor Tyndall 
by introducing a bundle of ‘‘old hay” into his 
laboratory. Henceforth there was evidence of 
fermentation in boiled fluids without stint; desic- 
cated germs were said to be everywhere—germs 
capable of resisting even two, three, four, and more 
hours of boiling, as he thought, everywhere sur- 
rounded him and got into his infusions. 
These, at least, were the hypotheses by which 
Professor Tyndall endeavoured to reconcile his 
earlier with his later results. But two things strike 
one as very unsatisfactory in regard to these hypo- 
theses and his method of supporting their cogency. 
In the first place it may be observed that the fact 
of his having introduced a bundle of ‘‘ old hay” into 
the laboratory of the Royal Institution cannot be 
regarded as a satisfactory explanation of the results 
of myself and others who had been able to obtain 
fermentation in boiled fluids long before, without the 
aid of any such magician’s wand as this which Pro- 
fessor Tyndall had chanced to employ. 
Secondly, there is the very dubious nature of the 
evidence by which he sought to support his 
interpretation, and the absence of anything in 
what he had published on the subject which gave 
a definite and independent foundation to this in- 
terpretation. Thus, to take one illustration, in the 

