To give an idea of the rapidity with which this ferment multiplies, we may state that our sketch (Fig. 40) was made under the following conditions:—On April 28th, 1874, we caused a flask of wort to ferment by means of a trace of “high” yeast. On the morning of the next day, that is fourteen hours afterwards, an appreciable deposit of yeast had formed, and some frothy patches appeared on the surface of the liquid, showing that fermentation had set in. On May 1st we decanted the beer, substituting for it water sweetened with 10 per cent. of sugar. On May 2nd we decanted the sweetened water, and substituted a fresh quantity containing the same percentage of sugar. On May 3rd, at mid-day, we took some of the fermenting liquid from this flask and put it into a flask of wort; five hours after the introduction of the ferment we made the sketch in question. The field is covered with branching clusters, the groups being sketched exactly as they occurred in the field. Their activity was due to the condition of the ferment, and to the perfect fitness of the nutritive medium for its vegetation. In sweetened water the budding of the cells was considerably less active; no branching groups of cells are to be found. Budding, nevertheless, occurs to a considerable extent, but it is limited to one bud, or two at the most, to each cell. Fermentation in pure sweetened water is mostly correlative with the duration of vital activity in the globules already formed. [Illustration: Fig. 40.] Let us next suffer our yeast to exhaust itself by keeping it in a great excess of sweetened water for a very long time; we shall then be able to observe its process of revival, and see if we can find any facts analogous to those presented by _saccharomyces pastorianus_ (Chapter V. § 1). With this object in view, on May 6th, 1874, we impregnated two fresh flasks of sweetened water with some of the contents of the before-mentioned flask, which we had refilled with sweetened water on May 2nd. On May 13th we decanted the liquid, which was still very sweet, from one of these two fresh flasks, which could hardly be said to have fermented at all—the quantity of yeast in them being so small—and replaced it with some wort. Strange to say, on the morning of the 14th we found an appreciable growth of yeast, and a froth of carbonic acid gas on the surface of the liquid. The yeast therefore was not dead, although its fermentative powers had been exhausted. There was, however, no remarkable feature in connection with its revival, nor did we find the slightest trace of any of the elongated ferment-form. What we got was simply the ramified groups of “high” yeast again, in round cells, but nothing more.