SP ONTANEO US-GENERA TIOX CONTB VERS Y. 459 



what air does or does not contain, since I have long ago shown .... 

 that boiled fluids can be made to putrefy and swarm with bacteria in 

 closed flasks, from which air and whatever it may contain has been 

 expelled." ' The same reasoning also obtains in his communication to 

 the Lancet 3 and to JVature* The result is clear. The doctrine of 

 " spontaneous generation " rests upon exceptions for its truth. In rare 

 instances, and in special infusions, bacteria have appeared after pro- 

 longed boiling. After a careful sifting of the evidence, the meagre- 

 ness of the testimony is striking. All that can be fairly taken at all, 

 when justly weighed, if taken altogether, is not equal to the evidence 

 given by Dr. Burdon-Sanderson. 4 But it is well known that, while 

 admitting and publishing the facts, he ignores absolutely Dr. Bas- 

 tian's inference. And surely this is the truer philosophy. Let it be 

 granted that, by means not now explicable, the germs of bacteria, de- 

 structible in filtered infusions at a boiling temperature, are feebly, and 

 at times, able to survive a slight continuation of the boiling-point in 

 infusions containing solid particles without apparent injury is not 

 that a ground for inquiring the reason why, rather than for inferring 

 "spontaneous generation?" If we can prove that in ninety-nine 

 cases out of one hundred actual germs are destroyed at 212 Fahr.,but 

 that, in exceptional circumstances, the remaining one case yields bac- 

 teria after exposure to 212 Fahr. for some minutes, is not that a 

 reason for inferring, and looking for, some protective influence upon 

 the germ, rather than launching into an hypothesis of a new mode 

 of origin ? 



That the medium in which minute organic forms are subjected to 

 heat exerts an influence on their subsequent deportment I can abun- 

 dantly prove. I am equally convinced that the deathq:>oint of bac- 

 teria-germs hovers very near the boiling-point of water a conviction 

 amply sustained by fact. This being so, the survival, as germs, of 

 some few, amid incalculable myriads, by some accidental protection, 

 is surely possible. So that, indeed, all true work now should be a 

 study of the germ and its properties, and a discovery by patient 

 research of the life-history of the organism. 



The valueless nature of mere temperature experiments on such 

 organisms, as tests of their ability to survive, without a knowledge 

 of their life-history, Dr. Bastian, icithout knowing it, has made suffi- 

 ciently plain. He gives a brilliant illustration styled by himself 

 " typical" of the futility of his own method. Consider the facts. 



In our "Researches" on the monads, my colleague and myself 

 made it a special point to institute a series of investigations on the 

 points of temperature which the adults, and the spores, of each form 

 studied could resist. The results were as unexpected as they were 

 remarkable. Only the results can here be stated. Taking the spore- 



1 Times, January 29, 1876. 3 February 10, 1876. 



2 February 5, 1876. 4 Nature, January 9, 1873, vols. vii. and viii. 



