536 FltAGMttNTS OF SCI UN CE. 



hold of you that a living thing is easily generated because 

 it is small. Both the yeast-plant and the barley-plant lose 

 themselves in the dim twilight of antiquity, and in this 

 our day there is no more proof of the spontaneous genera- 

 tion of the one, than there is of the spontaneous generation 

 of the other. 



I stated a moment ago that the fermentation of grape- 

 juice was spontaneous; but I was careful to add, "in what 

 sense spontaneous will appear more clearly by and by." 

 Now this is the sense meant. The wine-maker does not, 

 like the brewer and distiller, deliberately introduce either 

 yeast, or any equivalent of yeast, into his vats; he does not 

 consciously sow in them any plant, or the germ of any 

 plant; indeed, he has been hitherto in ignorance whether 

 plants or germs of any kind have had anything to do with 

 his operations. Still, when the fermented grape- juice is 

 examined, the living Torula concerned in alcoholic fermen- 

 tation never fails to make its appearance. How is this? 

 If no living germ has been introduced into the wine- vat, 

 whence comes the life so invariably developed there? 



You may be disposed to reply, with Turpin and others, 

 that in virtue of its own inherent powers, the grape-juice 

 when brought into contact with the vivifying atmospheric 

 oxygen, runs spontaneously and of its own accord into 

 these low forms of life. I have not the slightest objection 

 to this explanation, provided proper evicence can be 

 adduced in support of it. But the evidence adduced in 

 its favor, as far as I am acquainted with it, snaps asunder 

 under the strain of scientific criticism. It is, as far as I 

 can see, the evidence of men, who however keen and 

 clever as observers, are not rigidly trained experimenters. 

 These alone are aware of the precautions necessary in 

 investigations of this delicate kind. In reference, then, 

 to the life of the wine-vat, what is the decision of experi- 

 ment when carried out by competent men? Let a quantity 

 of the clear, filtered "must" of the grape be so boiled as 

 to destroy such germs as it may have contracted from the 

 air or otherwise. In contact with germlessair the un con- 

 taminated must never ferment. All the materials for 

 spontaneous generation are there, but so long as there is 

 no seed sown, there is no life developed, and no sign of 

 that fermentation which is the concomitant of life. Nor 

 need you resort to a boiled liquid. The grape is sealed by 



