Fearing that our yeast might not have remained for a sufficient time in the sweetened water for exhaustion, we set aside, for a whole year, the other flask which we had prepared on May 6th. On May 16th, 1875, we decanted the sweetened liquid and replaced it with wort. This time, however, there was no revival of the yeast; it had perished. Fortunately, we had also saved the flask of yeast and sweetened water which was prepared on May 2nd, 1874, as already mentioned, and in this case, as will be seen, the vitality of the yeast had not been extinguished, doubtless, in consequence of the formation of what we shall presently designate by the name of _aërobian ferment_. On May 16th, 1875, we decanted the liquid from this last flask, and replaced it with wort. On the next day the surface of the wort was covered with a thin froth, indicating the commencement of fermentation. The microscope revealed nothing extraordinary, or indicative of the fermentation of any special ferment. To assure ourselves that our ferment had remained “high,” we sowed some of it in a fresh flask of wort on May 19th, and then, seven hours after impregnation, submitting it to examination, we could find nothing but ramified groups in fine condition, without a single elongated cell, indeed, it would have been impossible to find a more beautiful specimen of “high” yeast, or one of a more decided character. It would seem, therefore, that “high” yeast cannot, under any circumstances, assume the form and character of the ferment _saccharomyces pastorianus_, or of other known ferments. We are justified, therefore, in regarding it as a distinct species of ferment, an opinion which is supported by other circumstances. 1. In equal quantities of saccharine wort a considerably greater growth of “high” yeast is obtained than of other yeasts. We need no very rigorous proofs to convince ourselves of this fact: for by simply causing equal volumes of the same wort to ferment, the one being pitched with _saccharomyces pastorianus_, for example, the other with “high” yeast, we shall obtain a perceptibly greater volume of “high” yeast than of the other, in certain cases even five or six times as much. 2. “High” yeast is of a tougher texture than the others, separating, when the fermented liquor and its deposit is shaken up, into lumps which refuse to disappear; whereas _saccharomyces pastorianus_ diffuses through the whole liquid with the greatest ease. 3. “High” yeast produces a special beer, with a peculiar flavour, well known to consumers, but little esteemed at the present day. Hence the gradual displacement of breweries worked on the old “high” fermentation system by others in which “low” yeast (of which more anon) alone is employed.