STUDIES ON FERMENTATION. 309 



presence of minute quantities of air brought into contact with 

 a liquid undergoing butyric fermentation would prevent the 

 continuance of that fermentation, or even exercise any check 

 upon it ? We have not made any direct experiments upon this 

 subject ; but we should not be surj)rised to find that, so far from 

 hindering, air may, under such circumstances, facilitate the 

 propagation of the vibrios and accelerate fermentation. This 

 is exactly what happens in the case of yeast. But how could 

 we reconcile this, supposing it were proved to be the case, with 

 the fact just insisted on as to the danger of bringing the butyric 

 vibrios into contact with air ? It may be possible that life without 

 air results from habit, whilst death through air may be brought 

 about by a sudden change in the conditions of the existence of the 

 vibrios. The following remarkable experiment is well known : 

 A bird is placed in a glass jar of one or two litres (60 to 120 

 cubic inches) in capacity, which is then closed. After a time 

 the creature exhibits every sign of intense uneasiness and 

 asphyxia long before it dies ; a similar bird of the same size is 

 introduced into the jar ; the death of the latter takes place 

 instantaneously, whilst the life of the former may still be pro- 

 longed under these conditions for a considerable time, and there 

 is no difficulty even in restoring the bird to perfect health by 

 taking it out of the jar. It seems impossible to deny that we 

 have here a case of the adaptation of an organism to the gradual 

 contamination of the medium ; and so it may likewise happen 

 that the anaerobian vibrios of a butyric fermentation, which 

 develop and multiply absolutely without free oxygen, perish 

 immediately when suddenly taken out of their airless medium, 

 and that the result might be different if they had been gradu- 

 ally brought under the action of air in small quantities at a 

 time. 



We are compelled here to admit that vibrios frequently 

 abound in liquids exposed to the air, and that they appropriate 

 the atmospheric oxygen, and could not withstand a sudden 

 removal, from its influence. Must we, then, believe that such 

 vibrios are absolutely diflferent from those of butyric fermenta- 



