108 LOUIS PASTEUR. 



But we have not yet related all. So far, all these 

 conclusive experiments had been made only on organic 

 liquids, very putrescible it is true, but which had all 

 been subjected to boiling or even to temperatures 

 higher than 100 degrees Centigrade. The partisans 

 of spontaneous generation might then be justified in 

 saying that if the precaution had been taken of putting 

 into contact with pure air natural organic liquids in a 

 state compatible with the operations of animal and vege- 

 table life, the results would have been different. Under 

 such conditions, life would have appeared spontaneously 

 in the production of microscopic organisms. None of 

 Pasteur's opponents had formulated this argument; 

 but Pasteur himself, who had within him an adversary 

 always present, always on the alert, prepared to yield 

 only to accumulated proofs, saw this objection. 

 He was not satisfied until he had succeeded in com- 

 pletely refuting it. Having by means of ingenious 

 experimental arrangements deprived some air of all 

 living germs, he placed in contact with this pure 

 air the most putrescible liquids, particularly venous 

 blood, arterial blood, and urine. He took these 

 liquids directly from the veins, the arteries, and the 

 bladders of animals in full health. No alteration 

 was produced. In due time a chemical absorption of 

 small quantities of oxygen took place, but neither 

 fermentation nor putrefaction, nor the smallest deve- 

 lopment of bacteria, of vibrios, or of mould. After 



