SPONTANEOUS GENERATION. 585 



momentary exposure to the boiling temperature, while 

 others withstand it for several hours. Most of our ordinary 

 seeds are rapidly killed, while Pouchet made known to the 

 Paris Academy of Sciences in 1866, that certain seeds, 

 which had been transported in fleeces of wool from Brazil, 

 germinated after four hours 7 boiling. The germs of the 

 air vary as much among themselves as the seeds of the 

 botanist. In some localities the diffused germs are so tender 

 that boiling for five minutes, or even less, would be sure to 

 destroy them all; in other localities the diffused germs are 

 so obstinate, that many hours' boiling would be requisite to 

 deprive them of their power of germination. The absence 

 or presence of a truss of desiccated hay would produce 

 differences as great as those here described. The greatest 

 endurance that I have ever observed and I believe it is the 

 greatest on record was a case of survival after eight hours' 

 boiling. 



As regards their power of resisting heat, the infusorial 

 germs of our atmosphere might be classified under the fol- 

 lowing and intermediate heads: Killed in five minutes; not 

 killed in five minutes but killed in fifteen; not killed in 

 fifteen minutes but killed in thirty; not killed in thirty 

 minutes but killed in an hour; not killed in an hour but 

 killed in two hours; not killed in two but killed in three 

 hours; not killed in three but killed in four hours. I have 

 had several cases of survival after four and five hours' boil- 

 ing, some survivals after six, and one after eight hours' 

 boiling. Thus far has experiment actually reached; but 

 there is no valid warrant for fixing upon even eight hours 

 as the extreme limit of vital resistance. Probably more 

 extended researches (though mine have been very extensive) 

 would reveal germs more obstinate still. It is also certain 

 that we might begin earlier, and find germs which are 

 destroyed by a temperature far below that of boiling water. 

 In the presence of such facts, to speak of a death-point of 

 bacteria and their germs would be unmeaning but of 

 this more anon. 



"What present warrant," it has been asked, "is there 

 for supposing that a naked, or almost naked, speck of 



high scientific importance should not have been more thoroughly 

 explored. Here the scoundrels who deal in killed seeds might be 

 able to add to our knowledge. 



