78 ORIGIN OF LOWEST ORGANISMS. 



tremely foetid odour. The fluid had an acid re-action, 

 and when examined microscopically, multitudes of 

 Bacteria, Vibriones and Leptothrix filaments were found 

 the movements of the Bacteria being very languid. 



FOURTH SET OF EXPERIMENTS (XXXI. XXXVII.). 



/;. Fluid in contact with ordinary Air and its Particles ; Flask 

 Sealed after the Fluid had become Cold. 



No. XXXI. Healthy Urine remained in the warm bath 

 for twenty-eight days without undergoing the least 

 change. 



No. XXXII. Simple Turnip Infusion remained in the 

 warm bath for twenty-eight days without undergoing any 

 appreciable change.* On breaking the neck of the 

 flask, the fluid was found to be quite odourless. With 

 its neck quite open, the flask was replaced in the water- 

 bath. During the first forty-eight hours it underwent 

 no apparent change, though at the end of seventy-two 

 hours a slight general turbidity was noticeable, and an 

 examination of a drop of the fluid (still odourless), 

 showed a number of minute but very active Bacteria.^ 



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



No. XXXIII. Simple Turnip Infusion showed no 

 change after eight days' immersion in the warm bath. 



* Experiment No. 8, recorded in ' Nature,' 1870, No. 36, p. 194, 

 may be compared with this and No. XXXIII. 



f This experiment should be compared with Nos. XVIII. and 

 XXXIII. It seems to show that if some fermentable fluids can 

 be kept for a time under conditions in which they will not fer- 

 ment, the constitution of the fluid, instead of remaining the same, 

 undergoes a slow alteration by which it is rendered absolutely 

 less fermentable, even when exposed to the most favouring 

 influences. 



