STUDIES ON FERMRNTATTO.V. 91 



these flasks by the letters A, B, C. On the following day 

 the spores germinated, and the liquid became full of flakes 

 of mycelium, some of which came to the surface to fructify. 

 The temperature varied between 25° C. and 30° C. (77° to 

 86° F.). 



On June 22nd, small patches, with whitish borders and green 

 centres, developed on the liquids. "We then shook up the flask 

 A, in order to submerge the plant and the spores.* We also 

 shook the flask B, after observing the precaution of sealing up 

 the slender bent tube.f The flask C was attached on one side 

 to an aspirator, on the other to a tube filled with cotton, and 

 every day we renewed the air in it. 



During the weeks and months over which our observations 

 extended, there was not the least formation of yeast in these 

 flasks ; moreover, we have frequently repeated this and other 

 experiments of a similar kind, without ever detecting the 

 appearance of either ordinary yeast or any other true alcoholic 

 ferment. The experiments may be made with saccharine juices 

 that are highly favourable to the development of bacteria and 

 lactic ferment. These latter appear equally incapable of trans- 

 formation into yeast, which has never been seen to develop in 

 experiments where they were used, if proper precautions have 

 been taken to secure a pure growth. Should we neglect any of 

 the precautions that are necessary to secure the purity of our 

 spores, we may of course obtain difierent results. If, for 

 instance, we sow spores oi pmicillium grown in free contact with 



* To shake tlie liquid witliout danger of introducing exterior particles 

 of dust, we apply the flame of the spirit lamp to the drawn-out neck of 

 the flask, and close up the open end ; we may then shake our flask with- 

 out risk. We must afterwards reopen the end of the drawn-out neck for 

 the purpose of re-establishing communication with the exterior air. 



t The flask B was closed with the lamp in consequence of one of the 

 objects of these experiments being to test M. Trecul's experiments on the 

 transformation oi penidlliwn into ferment. Strangely enough, according 

 to M. Trecul, as we shall see later on, the spores of penicillium refuse to 

 change into ferment, if the vessels in which they are sown are not 

 " perfectly air-tight." 



