68 BACTERIA. 



was followed by a typical fermentation in the fluid, from 

 which air was excluded by the film of oil spread over the 

 surface. On microscopical examination of both the artificial 

 and the spontaneous fermentations, he found u vibriones " 

 ifj, thick and 5o/i long. It was objected that in the 

 spontaneous fermentation a certain quantity of air must 

 necessarily remain in the fluid in which the organism was 

 growing, so that the presence of oxygen could not be 

 inimical to the growth of this " anaerobic " organism (a 

 name that Pasteur gave to those organisms that are not 

 dependent upon the oxygen of the air for their growth and 

 development). He met this objection with proof that, 

 grown along with other organisms, such as bacterium 

 termo, which were dependent upon free oxygen for their 

 existence, the latter developed and grew for a short time in 

 the fluid and so used up what oxygen there was present 

 in solution, at which point they were unable to develop 

 further, so that other resulting changes must be due to the 

 growth of the special anaerobic organism. Passing from 

 the butyric acid fermentation, and taking it as an analogy, 

 Pasteur continued his researches on putrefactive processes 

 in which nitrogenous substances and acrid and offensive 

 smelling materials are formed, and he eventually came to 

 the conclusion, which had already been expressed by Mit- 

 scherlich in 1843, that as yeasts gave rise to fermentation so 

 u vibriones " must be the cause of putrefaction ; and, going 

 further, he assumed, what has since been proved to be 

 erroneous, that the whole of the vibriones of putrefaction 

 were anaerobic, that is, they could give rise to their specific 

 products only when they were removed from the influence 

 of the action of the oxygen of the air. 



In connection with the subject of anaerobiosis, Pasteur pointed out that 

 the mycoderms known as " flower of wine," "flower of vinegar," &c., 

 were able to produce different forms of fermentation according to the 

 presence or absence of oxygen. Mycoderma aceti, for instance, bringing 

 about the splitting up of sugar into alcohol, i.e,, setting up an alcoholic 

 fermentation when there is too little oxygen present, but in presence of 

 abundance of oxygen giving rise to the formation of acetic acid, then setting 

 up what is known as the acetic fermentation. 



These researches eventually led Pasteur to the conclusion 

 well stated by Duclaux, that " whenever and wherever there 

 is decomposition of organic matter, whether it be the case 



