xxx vi THE BEGINNINGS OF LIFE. 



Vibrio could be detected, and the fluid was still quite 

 odourless 1 . 



No. XIX. Neutral Turnip Infusion + \ gr. 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 fcetid, 

 whilst its re-action had become slightly acid. Portions of the 

 pellicle were found to be made up by aggregations of 

 Bacteria, Vibrtones, and an abundance of Leptothrix filaments. 

 The Baderia all exhibited very languid movements. 



e. Fluid (in vacuo) 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. 



1 This again is a most instructive experiment when compared with 

 Nos. XVI. and XX., in which portions of the same infusion were 

 employed. The results in No. IX. would lead us to believe that a 

 vegetable infusion which does not ferment, does, nevertheless, undergo 

 some changes in molecular composition, and this notion seems to derive 

 confirmation from the present experiment. Some of the same solution 

 which has been kept for a time (twelve days) from contact with atmo- 

 spheric particles, subsequently, even when fully exposed to the air, 

 undergoes no apparent change for six days, and then, instead of becom- 

 ing filled with Bacteria, swarms only with Torula. Yet the infusion in 

 this condition was perfectly capable of nourishing Bacteria, as I subse- 

 quently 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 ? 



