ORIGIN OF LOWEST ORGANISMS. 75 



great part, sunk to the bottom of the flask, though its 

 place on the surface was already taken by a new, though 

 thin, scum-like layer. After seventy-two hours, the 

 flask was opened ; there was no fetid odour of the 

 fluid, and its re-action was still neutral. Examined 

 microscopically the fluid showed an abundance of 

 Bacteria, and also of short monilated filaments. There 

 were, however, none of the ordinary kind of Vibriones, 

 and no Leptothrix. All the Bacteria exhibited very 

 languid movements. 



THIRD SET OF EXPERIMENTS (XXII. XXX.). 



a. Fluid exposed to Air in a Flask with a short Open Neck. 



No. XXII. Urine in twenty-four hours showed no change ; 

 though in forty-six hours the turbidity was well marked.* 

 Examined microscopically it was found to contain an 

 abundance of Bacteria. 



b. Fluid in contact mnth Ordinary Air and its Particles ; Neck 



of Flask Sealed after the Fluid had become Cold. 



No. XXIII. Urine in eighteen hours showed a distinct 

 pellicle, though there was not much general turbidity. 

 During the next few days the old pellicle fell to the 

 bottom, and a new one formed. 



c. Fluid in a Bent Neck Flask, having Eight acute Flexures. 



No. XXIV. Urine in forty-eight hours showed no change. 

 After twelve days there was still no general turbidity, 



Some of the same fluid, exposed in a similar flask, without 

 previous boiling, became turbid in eight hours, and lighter in 

 colour ; whilst, after twenty hours, the turbidity was extremely 

 well-marked. 



