STUDIKS ON FERMENTATION. 29 



just reviewed, a more detailed account of which may be 

 found in our Memoir published in the A/iiiaks cie Chimie et 

 de Physique, for 1862, under the title Memoire sur les corpuscules 

 organises en suspension dans Patniospltere. Examen de la doctrine 

 des generations spontanees. The shape of the flask represented 

 in Fig. 4 only differs from that of the preceding one in having 

 a second little tube attached to the globular part of the flask ; 

 this presents great advantages for difi'erent objects of study, and 

 it was adopted in the subsequent investigations detailed in 

 this work. 



This flask will permit us to study without difficulty every 

 separate kind of microscopic organism in the liquid best adapted 

 to it without fear, if we take reasonable precautions, that the 

 subject of our study may become associated with other organisms, 

 the accidental presence of which cannot fail to seriously affect 

 the results of our observations. 



Let us use one of those flasks in our experiment on yeast, at 

 the same time expressly assuming that the minute germs of 

 yeast are free from all contamination by foreign germs, an 

 object which we shall learn how to realize by a variety of 

 methods in a subsequent chapter. 



Let us introduce some wort into our flask (Fig. 4) ; then, 



Fig. 4. 



after we have fitted an india-rubber tube to the little supple- 

 mentary tube, let us boil the liquid ; the steam, finding an 

 easier exit through the india-rubber opening than through the 

 drawn-out tube, will rush out through the india-rubber tube, and 

 thus, as it passes, destroy any germs which may be adhering to 

 the sides of the little supplementary tube. If we close tlie india- 

 rubber tube by means of a glass stopper, the steam will imme- 



