272 FRAGMENTS OF SCIENCE 



jection to this explanation, provided proper evidence can 

 be adduced in support of it. But the evidence adduced 

 in its favor, as far as I am acquainted with it, snaps asun- 

 der 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 in- 

 vestigations of this delicate kind. In reference, then, to 

 the life of the wine-vat, what is the decision of experiment 

 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 germless air the uncontami- 

 nated must never ferments. All the materials for sponta- 

 neous generation are there, but so long as there is no seed 

 sown there is no life developed, and no sign of that fer- 

 mentation which is the concomitant of life. Nor need you 

 resort to a boiled liquid. The grape is sealed by its own 

 skin against contamination from without. By an ingen- 

 ious device, Pasteur has extracted from the interior of the 

 grape its pure juice, and proved that in contact with pure 

 air it never acquires the power to ferment itself, nor to 

 produce fermentation in other liquids.* It is not, there- 

 fore, in the interior of the grape that the origin of the life 

 observed in the vat is to be sought. 



What then is its true origin? This is Pasteur's an- 

 swer, which his well-proved accuracy renders worthy of 

 all confidence. At the time of the vintage microscopic 

 particles are observed adherent, both to the outer surface 



* The liquids of the healthy animal body are also sealed from external con- 

 tamination. Pure blood, for example, drawn with due precautions from the 

 veins, will never ferment or putrefy in contact with pure air. 



