THE BEGINNINGS OF LIFE. 361 



ments, no fair critic could reasonably object to the in- 

 ference that the organisms found were living, simply 

 because they only exhibited languid movements more or 

 less indistinguishable from mere molecular or Brownian 

 movements. The property of reproduction is a fun- 

 damental attribute of living things ; the power of 

 performing extensive movements is not, That repro- 

 duction has taken place must be obvious to all. How 

 else could a clear fluid, within an hermetically-sealed 

 vessel, become turbid owing to the presence of myriads 

 of Bacteria ? How else could a thick pellicle form on 

 such a solution composed of densely interlaced Bacteria., 

 ^ and Leptothrix filaments ? And, moreover, 



although in the fluid from some of the flasks the move- 

 ments of the contained Bacteria were so languid as to be 

 scarcely distinguishable from Brownian movements, in 

 that of others (as, for instance, in Exps, 4 and 5) the 

 movements were very active and unmistakeably vital, 

 That the vessels were in no way cracked, and that the 

 vacuum was in some cases still partially preserved, I 

 have thoroughly satisfied myself 1 . For the rest, the 



1 This is easily done by carefully heating the end of the neck of the 

 flask (before breaking it), and then softening it with the blow-pipe 

 flame. The insinking of the softened glass is a sure sign that the 

 vacuum is still more or less preserved. The amount of gas liberated 

 in different cases varies very much. In many instances it is not suffi- 

 cient to establish an equilibrium with the external atmospheric pressure, 

 though occasionally (even when the fluids were originally contained 

 in vacua) the internal tension from liberated gases exceeds the external 

 atmospheric pressure. 



