196 PASTEUR: THE HISTORY OF A MIND 



permitting the inoculation of the liquid by removing 

 the glass stopper which closed the rubber tube attached 

 to the straight tubulure. In this flask the culture is in 

 contact with air. When there is need of provoking a 

 fermentation in the absence of air, the straight tubulure 

 is connected by means of its rubber tube with a matrass 

 sufficiently small for the liquid to fill it completely. 

 In order to make with this apparatus a study of the 

 transformation of the mycoderma into yeast, it is 



FIG. 15. Apparatus used by Pasteur in his study of alcoholic and other 

 fermentations. 



sufficient to sow with the flowers of wine an alcoholic 

 liquid, or a sugar solution placed in D, and to pour it 

 immediately, when the pellicle has formed, into the 

 matrass BC, where it finds the conditions of great depth 

 and of small free surface' existing in the flask of the first 

 experiment (Fig. 15). The details of the manipulation 

 necessary to realize this transfer in the absence of all 

 exterior germs are of little moment. The apparatus is 

 furthermore, complicated and has been advantageously 

 replaced since. It suffices, however, to attain the 



