74 ORIGIN OF LOWEST ORGANISMS. 



No. XIX. Neutral Turnip Infusion+ igr. of Cheese, 

 showed no perceptible change in twenty-four hours, 

 though in thirty-six hours there was a well-marked 

 pellicle on the surface. When the neck of the flask 

 was broken after seventy-two hours, the fluid was found 

 to be very foetid, whilst its re-action had become slightly 

 acid. Portions of the pellicle were found to be made 

 up by aggregations of Bacteria, Vibriones, and an abund- 

 ance of Leptothrix filaments. The Bacteria all ex- 

 hibited very languid movements. 



e. Fluid (in vacua] in a Flask which had been Sealed during 

 Ebullition. 



No. XX. Simple Turnip Infusion in twenty-four hours 

 showed a very slight amount of turbidity ; in thirty- 

 six hours this had increased, and in forty-eight hours 

 there were multitudes of curdy flocculi floating in a 

 tolerably clear fluid. The flask was opened after 

 seventy-two hours, when there seemed to be only a 

 very slight inrush of air. The odour of the fluid was 

 somewhat foetid, and its re-action was acid. There were 

 multitudes of Bacteria and Vibriones, partly separate 

 and partly aggregated (constituting the flocculi above 

 mentioned). The separate Bacteria exhibited only very 

 languid movements. 



No. XXI. Neutral Turnip Infusion + \ gr. of Cheese, 



showed a well-marked pellicle on its surface in twenty- 

 four hours. In thirty-six hours the first pellicle had, in 



apparent change for six days, and then, instead of becoming 

 filled with Bacteria, swarms only with Tor nice. Yet the infusion 

 in this condition was perfectly capable of nourishing Bacteria, 

 as I subsequently proved by inoculating it. Why then was it 

 not inoculated by the living Bacteria, with which the air is 

 thought by some to be teeming ? 



