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of these active monads was placed for about five minutes on a 
glass slip in a water oven, maintained at a temperature of 
140° F. All the movements of the monads ceased from that 
time, and they never afterwards showed any signs of life.”* 
This is 'precisely our experience . But now mark the reasoning. 
This monad was killed at 140° F., but it teas found in an infu- 
sion that had been heated up to 275° F. ; therefore it must 
have originated de novo. 
But it has been shown that the monad has germs, and that 
these have a power of resisting heat up to 300° F. — that is to 
say, 25° F. higher than that to which Dr. Bastian’s infusion was 
exposed — and therefore , by the logic of facts, the monads found 
were not a result of “spontaneous generation,” but were the 
natural outcome of a genetic product contained in the infusion , 
and which the heat employed could not destroy. 
We need no stronger proof of the futility of reasoning con- 
cerning the thermal death-point of a minute organism where 
developmental history is wholly unknown. Yet so confident is our 
experimenter of his result that he says: “Nothing that has yet 
been alleged, by way of objection to the admission of spontaneous 
generation as an everyday fact, at all effects such experiments 
as these. The shortest way out of the difficulty would, therefore* 
be to doubt the facts.” But I think I have shown a still 
shorter way “ out of the difficulty,” and that, without the 
discourtesy of doubting Dr. Bastian’s experimental “ facts.” 
The truth, then, is that Dr. Bastian had no real knowledge of 
the monad ; but he argued as if he had. Hence assumed 
premises led to a false and fatal conclusion. 
He is simply repeating this in his latest attitude in reference 
to the question of the mode of origin of bacteria. Compelled 
to yield all else, he throws up a rampart round his exceptional 
flasks, and declares “ spontaneous generation ” to be impreg- 
nable — an inviolable law of nature. Dr. Tyndall is plainly told 
that his knowledge is insufficient, that he has mistaken the 
meaning of the question, and that his mode of treating it is 
“ laughable ; ” f and all this arises from the fact that Professor 
Tyndall dealt with the question of the mode of origin of bacteria 
generally ; whereas, to have pleased Dr. Bastian, he ought to 
have explained some exceptional conditions to which he now 
points — the exceptions being more important than the rule ! 
What are the facts ? 
I. Dr. Tyndall has proved, in connection with a host of others, 
but in a more definite and precise manner, that in filtered 
infusions five minutes’ boiling does kill every form of bacteria. 
* “Evolution and the Origin of Life/’ p. 179. 
t “Lancet,” Feb. 5, 1876 ; and “Brit. Med. Journ.” Feb. 5, 1876. 
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