PROGRESS OF MIOROSCOPIOAL SCIENCE. 
265 
by me were in substance identical with those obtained by Pasteur 
and Professor Tyndall. The circumstance that Professor Tyndall 
did not encounter those examples of great resistance to sterilization 
by heat that I encountered, involves no contradiction in our results. 
His procedure was different from mine, but our results were the same. 
We both succeeded by boiling in sterilizing our infusions without 
impairing their aptitude for the growth of bacteria. As well might 
we say that two chemists contradict each other when they obtain the 
same metal from the same ore by different processes. 
It appears to me that the attitude of Dr. Bastian on the question 
of the origin of bacteria arises from what I may call the inverted 
significance which he attaches to the two contrasted results — barren- 
ness or fertility — which follow after boiling an organic infusion. 
Throughout the controversy. Dr. Bastian speaks of the barren tubes 
and flasks as " failures " or " negative results " ; and he evidently 
regards the fertile tubes and flasks as " successful " experiments, 
having the force and authority of "positive" results. The true view 
is just the reverse of this, and his misunderstanding on this point 
makes him blind to the overwhelming cogency of the case against 
him. "When the matter is duly considered, it is the barren flask that 
has the character of a positive result. For what does the experimenter 
set himself to do in these experiments ? He seeks to destroy by 
boiling all pre-existing bacteria in these infusions, and to leave un- 
impaired their powers of promoting the growth of bacteria. And it 
is found in fact that this latter quality is perfectly preserved in 
boiled infusions ; for they breed bacteria with the utmost luxuriance 
when they are reinfected from an extraneous source. When the 
experimenter finds that his infusions germinate after boiling, the 
prima facie probability is, that he has either applied the heat insuffi- 
ciently, or has permitted extraneous infection after boiling; for this 
is exactly what would occur if he failed in either of these points. 
But if the infusions remain barren, this is a new and unexpected con- 
sequence, and carries with it the weight and cogency of a positive 
result. The explanation of the fertile flask is thus ready at hand ; 
it is simply a faulty experiment ; but what possible explanation can 
be given of the barren flask, except that supplied by the panspermic 
theory ? When I take up one of the flasks or bulbs which have 
remained barren in my chamber for three or four years, though 
supplied with air (filtered through cotton-wool) and suitable heat, my 
wonder never ceases. Each one is a new experiment, every day 
repeated, and multiplied indefinitely ; day after day I ask myself. 
Why does it not germinate ? I compare it to a field in spring not 
yet sown, but ready for the reception of the seed : for if 1 withdraw 
the plug of cotton-wool and admit the dust of the air, or introduce a 
drop of water, all is changed ; in a few hours the stillness of years 
gives place to life and activity. I repeat, it is the fertile flask, and 
not the barren flask, that wears the complexion of a failure and of a 
negative result. The reluctance of some evolutionists to give up 
the spontaneous origin of bacteria is evidently due to the notion that 
this question is bound up with that of abiogenesis generally. This 
