STUDIES ON FERMENTATION. 119 



mycoderma, a more or less elongated structure, which would be 

 a convincing proof of the transformation that we were seeking, 

 if, indeed, such transformation were possible. 



Strange to say, everything happened in a manner that seemed 

 to realize our expectations. The saccharine worts in the flasks 

 in which we had mixed and submerged the mycoderma, fer- 

 mented in the course of a few days ; the yeast first appeared in 

 elongated shapes ; lastly, we could see under the microscope that 

 many of the cells or jointed filaments of mycoderma were inflated 

 and presented the appearance of undoubted gradations between 

 their natural state and that of the cells of yeast which soon 

 formed part of the deposit in the vessels. In spite of all this, 

 however, we were the victims of an illusion. 



In experiments conducted as we have just described, the 

 yeast which appears, and which soon sets up an active alcoholic 

 fermentation, is introduced in the first place by atmospheric air, 

 from which germs are constantly falling either upon the film 

 of mycoderma or upon the objects that are employed in the 

 successive manipulations. Two peculiarities in these experiments 

 first opened our eyes to the existence of this cause of error. We 

 sometimes found at the bottom of the flasks in which we had 

 submerged the efflorescence, along with the cells of mycoderma, 

 large, spherical cells of mucor nmcedo or racemosus, ferment-cells 

 that we shall soon learn to recognize in studying this curious 

 fungoid growth. The existence of mucor nmcedo or racemosus, 

 where we had only sown mycoderma mni, was to us a proof that one 

 or more spores of that mucor had been introduced by the surround- 

 ing air. If then, we reasoned, the air can introduce spores of 

 mucor into our field of operations, why should it not introduce 

 cells of yeast, especially in our laboratory ? Again, it sometimes 

 happened that a negative result was obtained. Harassed by 

 doubts about the reality of this transformation, which accorded 

 so well with the physiological theory of fermentation we had 

 been led to adopt, we repeated the experiments many times, 

 and in some cases we failed to detect any appearance whatever of 

 a transformation of mycoderma into yeast cells, although the 



