50 LOUIS PASTEUR. 



augmented in weight, feeding upon the sugar, and its 

 vitality was such that it contrived to build up the 

 complex materials of its own organisation by means 

 of sugar and purely mineral elements. 



In a second experiment, Pasteur demonstrated 

 that, notwithstanding their smallness and the pos- 

 sibility of confounding them with the amorphous 

 granules of caseine and gluten, the little particles of 

 lactic ferment were indeed alive, and that they, and 

 they only, were the cause of lactic fermentation. He 

 mixed with some water, sweetened with sugar, a small 

 quantity of a salt of ammonia, some alkaline and 

 earthy phosphates, and some pure carbonate of lime 

 obtained by precipitation. At the end of twenty-four 

 hours the liquid began to get turbid and to give off 

 gas. The fermentation continued for some days. 

 The ammonia disappeared, leaving a deposit of phos- 

 phates and calcareous salt. Some lactate of lime was 

 formed, and at the same time one could notice the 

 deposition of the little lactic ferment. The germs of 

 the lactic ferment had, in this case, been derived from 

 particles of dust adhering to the substances themselves, 

 of which the mixtures were made, or to the vessels 

 used, or from the surrounding air. The chapter on 

 spontaneous generation will render this clear. 



It suffices here to state that the results of this 

 second experiment were absolutely conclusive, and 

 that the theories of contact force or of communicated 



