BACTERIA. 121 



quires an acute and trained observer, provided with the best 

 means of search, to find a trace of it. When a small amount 

 of yeast is added to a solution of sugar, the whole of the 

 sugar will be remoleculized, producing carbonic acid and 

 alcohol within a few hours, with, apparently, no increase of 

 the yeast. In this instance, however, the yeast has grown, and 

 performed its function of remoleculization, under the most 

 difficult circumstances, for the reason that it is deprived of 

 the nitrogen necessary for the building up of its cellulose 

 and albumen. Under these circumstances the amount of yeast 

 may actually decrease, as was shown by Liebig many years 

 ago. Pasteur seems to have proven that in this case the 

 young yeast cells grow at the expense of the nitrogen in the 

 old cells, and thus destroy them to such an extent that the 

 whole quantity of the yeast is diminished, and the vital 

 energies of the plant weakened. This example serves to 

 show the wonderful power of these low organisms. 



Then we may take the example of the destruction of the 

 dead carcass. The history of the experimentation of the past 

 shows conclusively that it does not decompose, if protected 

 from these low organisms. Yet within a few days it is 

 swarming with this form of life, in the presence of which it 

 melts away like ice before a summer sun. It is first attacked 

 by one form, which consumes and throws out its waste pro- 

 ducts as long as it can grow in the continually increasing 

 quantity of its own excreta. Then it must give way to others 

 that have already appeared on the scene of action, to which 

 the waste products of the first are no hindrance. These, in 

 turn, very soon give way to still other forms, which again 

 remoleculize the waste products of all the former that may 

 retain a semi-solid or a liquid form, with any residue of the 

 original carcass that may still remain; and in an almost 

 incredibly short time the whole carcass has disappeared. The 



