8PONTA NBO U8 O KNERA TION. 585 



momentary exposure to the boiling temperature, while 

 others wiih.-tand it for scvural hours. Most of our ordinary 

 seeds are rapidly killed, wh <-t made known to the 



Paris Academy <>f Sciences in 1806, that certain 

 which had been transported in fleeces of wool from Brazil, 

 germinated after four hours' boiling. The germs of the 

 air vary as much among themselves as the seeds of the 

 botanist. In some 1m-;, so tender 



that boiling for live minutes, or even less, would be sun- i> 

 destroy them all; in other localities the diffused germs are 

 so obstinate, that many hours' boiling would be n^ui-it.- to 

 deprive them of their power of germination. Tin- absence 

 or presence of a truss of desiccated hay would prudm-e 

 differences as great ;is those here described. The greatest 

 endurance that I have ever observed and I I is tho 



"rd was a case of survival after eight hours' 

 boiling. 



As regards their power of resisting heat, the infu 

 germs of our atmosphere might be classified under the fol- 

 lowing and intermediate heads: Killed in live minutes; not 

 killed in five minutes but killed in lifteen; not killed in 

 fifteen minutes hut 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. 1 have 

 had several cases of survival after four and live 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 

 \ve might begin earlier, and lind germs which ail- 

 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 th-ir germs would be unmeaning but of 

 this more anon. 



What present wan has been asked, "is there 



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



high scientific importance hhuuM i, t 



explorrd II-T.- the Mcoutxlr. I, who deal in kill.-d mini* might be 



able to add t<> <>nr ku->u |. .:.-.- 



