THE LIFE-WORK OF PASTEUR. 237 



too freely supplied. Reverting to the development of the yeast-plant 

 and the alcoholic fermentation, he found that they also went on best 

 when free air was excluded. Thus, Liebig's dictum, that fermentation 

 is the result of the action of oxygen, must be reversed or abandoned. 

 The organisms working these processes were given the class-name of 

 a7icerobes, or beings that live without air. The French Academy's 

 impressions of the results of Pasteur's work were spoken by Dumas, 

 who said to him, "In the infinitely little of life you have discovered a 

 third kingdom to which belong those beings which, with all the pre- 

 rogatives of animal life, have no need of air to live, and find the heat 

 they require in the chemical decompositions they provoke around 

 them," The place of the organisms in the economy of Nature had not 

 yet been fixed, but Pasteur was able to declare : " Whether the progress 

 of science makes the vibrion a plant or an animal, is no matter ; it is 

 a living beino: endowed with motion, that lives without air and is 

 ferment." It would be mere repetition to follow the experiments 

 in putrefaction, where Liebig had denied that living organisms have 

 any place, into which Pasteur carried the same methods and obtained 

 the same results as in the case of fermentation. He proved that living 

 organisms have all to do with it. 



After M. Pasteur had been collecting his proofs for twenty years, 

 Dr. Bouillaud sharply asked in the Academy : " How are your micro- 

 scopic organisms disposed of? What are the ferments of the fer- 

 ments ? " He, as well as Liebig, believed the question could not be 

 answered. Pasteur proved, by a series of the parallel experiments of 

 the kind that have since become familiar, that oxygen deprived of its 

 germs is incapable of producing fermentation or putrefaction, even 

 after years, while the same substances are acted upon at once if the 

 germs are present ; and then answered that the ferments are destroyed 

 by a new series of organisms — cerobes — living in the air, and these by 

 other serobes in succession, until the ultimate products are oxidized. 

 "Thus, in the destruction of what has lived, all is reduced to the 

 simultaneous action of the three great natural phenomena — fermenta- 

 tion, putrefaction, and slow combustion. A living being, animal or 

 plant, or the debris of either, having just died, is exposed to the air. 

 The life that has abandoned it is succeeded by life under other forms. 

 In the superficial parts accessible to the air, the germs of the infinitely 

 little serobes flourish and multiply. The carbon, hydrogen, and nitro- 

 gen of the organic matter are transformed, by the oxygen of the air 

 and under the vital activity of the rorobes, into carbonic acid, the 

 vapor of water, and ammonia. The combustion continues as long as 

 organic matter and air are present together. At the same time the 

 superficial combustion is going on, fermentation and putrefaction are 

 performing their work, in the midst of the mass, by means of the de- 

 veloped germs of the anserobes, which not only do not need oxygen to 

 live, but which oxygen causes to perish. Gradually the phenomena 



