296 LOUIS PASTEUR 



The following days, fermentation was active. Examining 

 yeast mixed with the froth that was expelled into the mercury by 

 the evolution of carbonic acid gas, we find that it was very fine, 

 young, and actively budding. 



February 3rd. Fermentation still continued, showing itself by a 

 number of little bubbles rising from the bottom of the liquid, which 

 had settled bright. The yeast was at the bottom in the form of 

 a deposit. 



February 7th. Fermentation still continued, but rery languidly. 



February Qth. A very languid fermentation still went on, discern- 

 ible in little bubbles rising from the bottom of the flask. 



Flask B, with air. 



January 2ist. A sensible development of yeast. 

 The following days, fermentation was active, and there was an 

 abundant froth on the surface of the liquid. 



February ist. All symptoms of fermentation had ceased. 





As the fermentation in A would have continued a long 

 time, being so very languid, and as that in B had been 

 finished for several days, we brought to a close our two ex- 

 periments on February gth. To do this we poured off the 

 liquids in A and B, collecting the yeasts on tared filters. 

 Filtration was an easy matter, more especially in the case 

 of A. Examining the yeasts under the microscope, im- 

 mediately after decantation, we found that both of them re- 

 mained very pure. The yeast in A was in little clusters, the 

 globules of which were collected together, and appeared 

 by their well-defined borders to be ready for an easy revival 

 in contact with air. 



As might have been expected, the liquid in flask B did 

 not contain the least trace of sugar; that in the flask A 

 still contained some, as was evident from the non-completion 

 of fermentation, but not more than 4.6 grammes (71 grains)- 

 Now, as each flask originally contained three litres of liquid 

 holding in solution 5 per cent, of sugar, it follows that 150 

 grammes (2,310 grains) of sugar had fermented in the flask 

 B, and 145.4 grammes (2,239.2 grains) in the flask A. The 

 weights of yeast after drying at 100 C. (212 F.) were 



For the flask B, with air.... 1,970 grammes (30.4 grains). 

 For the flask A, without air.. 1,368 grammes*. 



*This appears to be a misprint for 1.638 grammes=3S.3 grains. D. C. 



