218 THE EVOLUTION OF LIFE 
fermentative change in a fluid with the same facility 
that it might destroy germs supposed to be suc- 
cessively awakening to life and activity.1| When- 
ever an investigator has decided beforehand that 
one of these possibilities is not worth thinking 
of as an interpretation, the problem to his mind, 
becomes, of course, a simple one. And amidst 
all the conflicting nature of his evidence Profes- 
sor Tyndall never wavered in the steadfastness 
of his adhesion to the germ-theory. All through, 
with him, the question was always whether the 
germs were or were not killed with a given amount 
of heating. The other side of the question in 
dispute, the possible ‘‘ generating” power of the fluids 
employed, was wholly ignored. He declared, in 
fact, in Zhe 7zmes (June 18, 1877), in reference to 
1 A fairer way of testing Professor Tyndall’s notion may be found 
in some such manner as I have myself adopted. Thus, a hay-infusion 
was made in the ordinary way, which after filtration was found to be 
clear, of a dark sherry colour, and to have a neutral reaction. Nine 
tubes from three to four inches long and one inch in diameter were 
employed, which were thoroughly famdés. Having been rather more 
than half filled with the hay-infusion, the fluid in each was boiled for 
one minute and sealed during ebullition. These experiments were 
purposely made in the month of January, when the weather was rather 
cold, ranging from 32°-45° F. The tubes were kept outside the 
window, in the shade, and their position was reversed twice daily 
during four days, so as to allow plenty of time for the softening of any 
germs or spores that might be present either in the fluid or on the 
walls of the vessel. The tubes were then put into a can of water and 
raised with the water to the boiling-point—the boiling being continued 
for four minutes. During this second process of boiling two tubes 
were cracked, but the remaining seven were placed in the incubator 
at 115 F., with the following results: In 24-36 hours the fluid in all 
the tubes had become slightly turbid and lighter in colour, owing to 
the presence of swarms of Bacilli. I have obtained very similar 
results on other occasions, 
