184 ANNUAL OF SCIENTIFIC DISCOVERT. 



when putrefaction is in some sort restrained. It results from what 

 precedes, that contact with air is not necessary to the development of 

 putrefaction, but that, on the contraiy, if the oxygen, dissolved in a 

 putrescible liquid, is not removed by the action of special beings, pu- 

 trefaction will not occur, as the oxygen would cause the vibrions to 

 perish if they tried to develop themselves. 



" I shall now examine the case of free putrefaction in contact 

 with air. That which I have already said might make it appear that 

 it could not take place under such circumstances, as oxygen kills the 

 vibrions which excite it. Notwithstanding this, I shall demonstrate 

 that putrefaction in contact with air is more complete than when it is 

 effected under shelter from air. Let us go back to our aerated liquid, 

 this time exposed to contact with air in a wide-mouthed vessel. The 

 removal of the oxygen takes place as previously described. The dif- 

 ference is that the bacteriums, etc., do not perish, but propagate them- 

 selves to infinitude at the surface of the liquid which is in contact with 

 the air. They form a thin pellicle, which gradually thickens, falls into 

 rags to the bottom of the vessel, is formed again, and so forth. This 

 pellicle, with which is usually associated divers mucors and mucedines, 

 prevents the solution of oxygen gas in the liquid, and thus permits the 

 development of the vibrio-ferments. For them the vessel is as if closed 

 against the introduction of air. They can even multiply in the pellicle 

 at the surface, because they find themselves protected by the bacteri- 

 ums and mucors against too direct an action of the atmospheric air. 



" The putrescible liquid thus becomes the seat of two kinds of action, 

 very distinct, and which are in relation to the physiological functions 

 of the two kinds of beings that nourish themselves in it. The vibrions, 

 on one hand, living without the aid of atmospheric oxygen, determine, 

 in the interior of the liquid, acts of fermentation that is to say, they 

 transform nitrogenous substances into more simple, though still com- 

 plex, products. The bacteriums or the mucors burn these same pro- 

 ducts, and bring them back to the simple condition of binary compounds, 

 water, ammonia, and carbonic acid. 



" We have yet to distinguish the very remarkable case in which the 



/ 



putrescible liquid forms a layer of slight thickness with easy access to 

 atmospheric air. I shall demonstrate experimentally that both putre- 

 faction and fermentation may be absolutely prevented, and that the 

 organic matter will yield only to the operation of combustion. 



" Such are the results of putrefaction effected with free contact with 

 the atmosphere. On the contrary, in the case of putrefaction under 

 shelter from the air, the products of the doubling l of the putrescible 

 matter remain unchanged. This is what I meant when I said that 

 putrefaction in contact with air is a phenonemon, if not always more 

 rapid, at least more complete, more destructive of organic matter, than 

 putrefaction under shelter from air. In order to be better understood, ' 

 1 shall cite some examples. Let us putrefy I employ the word de- 

 signedly in this instance as a synonym of ferment, let us putrefy lac- 

 tate of lime sheltered from air. The vibrion-ferments will transform 

 the lactate into several products, one of which is always butyrate of 



1 " De dotiblement de la mati're putrescible." Pasteur means the products of 

 the nutrei'active fermentation, which lie 1ms described as complex, though more 

 simple than the original substances. 



