On December 28th bubbles of gas began to be evolved carrying up clusters of mycelium to the surface of the liquid. It was evident, therefore, that the quiescence in the test-glass attached to flask B, was solely due to deprivation of air, as had happened in the case of the test-glass attached to flask C, up to the date of October 31st. On this day, December 28th, we re-decanted the contents of the flask into the test-glass, and the following day a continuous but feeble fermentation proceeded. This lasted until January 22nd, although very sluggish in character; it is evident that these effects were exactly the same as those which took place in flask C.[76] We should observe before we proceed further, that we took specimens from the flasks A, B, C, at different times between June and January, and that the microscope never revealed the least trace of yeast in them. We may note besides that, during this interval, we impregnated fresh flasks of wort with specimens taken from the deposits in the flasks A, B, C, and that we always obtained reproduction of the _mucor_ and its peculiar fermentation without the least appearance of ordinary ferment. The inferences from the results that we have just detailed follow readily, and are besides of great interest. In the first place, it is evident that even if the _mucor mucedo_ may be able to produce alcoholic fermentation, it is totally incapable of changing into yeast. The two plants are necessarily and radically distinct, and, if different authors have succeeded in obtaining them mixed one with another in growths of _mucor_, this intermixture was doubtless the result of a spontaneous sowing of the yeast, the germs of which abound, particularly in the particles of dust existing in the atmosphere of any laboratory in which studies relating to fermentation are pursued.