AEROBIC LIFE AND ANAEROBIC LIFE 83 



developed this idea later. For the moment we may 

 content ourselves with saluting its dawn. 



This idea has, nevertheless, an indispensable com- 

 plement which we can and must give immediately. 

 There is oxygen everywhere, in the air and in the water. 

 It is in the liquid in which we have sown our bacillus 

 which is unable to bear the air, our anaerobic vibrio. 

 How is it that it can develop in this aerated medium? 

 It is because we have, unawares, sown with it in the liquid 

 some aerobic organisms which have consumed its oxygen, 

 and, this being achieved, have fallen inert to the bottom, 

 permitting the butyric vibrio to take possession of the 

 medium. If the liquid is in contact with the air some 

 of these aerobic organisms have remained on its surface. 

 There they continue to live, to swarm, and they form a 

 gelatinous layer which is. for the oxygen, a barrier as 

 impermeable as a wall of glass; all of it that is able 

 to penetrate is absorbed in the passage, and, thanks to 

 this aerobic life on the surface, the anaerobic life can 

 pursue its course in the depths without hindrance. 



Having come to this simple and satisfactory concep- 

 tion, it was not the moment for him to stop. Up to 

 this time we have observed only the phenomena of the 

 fermentation of sugar, or of the lactate of lime. Let 

 us now turn our attention to an albuminoid substance, 

 beef bouillon, egg albumen, meat macerated in water. 

 Let us, as we have done hitherto, begin the operation 

 by introducing into it a drop of an organic liquid under- 

 going putrefaction: we shall see the same phenomena 

 begin again. There is formed once more on the surface 

 of our liquid a living layer which will absorb the oxygen 

 and will leave the interior of the mass free for the 

 anaerobic life. If our liquid is contained in a closed flask, 

 one or several aerobic generations will dispel the oxygen, 

 and will leave the field free to the anaerobes. There 



