fermentations of wort either a distinctly “high” ferment, or a distinctly “low” one, properly so called; nor, further, have we ever obtained either one of these distinct kinds, with its industrial characteristics, in experiments on the ferments of fruits. What, then, was the origin of the “high” and “low” ferments now used by brewers? What was the nature of their original germs? These are questions which we are unable to answer, but we are very much inclined to think that we have here another example of the modifications which plants as well as races of animals undergo, and which become hereditary in the course of prolonged domestication. We know nothing of corn in its wild state, we cannot tell what its first grain was like. We know nothing of the silk-worm in its original state, and we are ignorant of the characters of the race that furnished the first egg. These reflections may seem to favour the supposition that there is a real difference between “high” yeast and “low” yeast, and that both of these differ from spontaneous ferments and the ferments of domestic fruits. These are propositions demanding most careful consideration, for it is generally admitted that these ferments become intermixed, that their morphological differences are merely a question of medium, and that the transition of one to the other is a simple matter. The following facts seem to contradict such statements. [Illustration: Fig. 39.] “High” Ferment.—Fig. 39 represents some “high” yeast taken from a deposit after fermentation, and Fig. 40 the same yeast in course of propagation in some aerated wort. In comparing “high” yeast with other alcoholic ferments at the same stage of development, there are three points which are especially striking: the diameter of its cells is relatively large, their general aspect is rounder, and when they are undergoing propagation their mode of budding produces a markedly ramified appearance, so that the cells always occur in clusters and branches. Fig. 40 gives a very exact idea of these characters. To investigate satisfactorily the branching habit of growth peculiar to this ferment we should examine it during the first few hours of its propagation, when, under the influence of the oxygen dissolved in the fermentable liquid, its vital activity is greatest. Later on, often on the day following the sowing, the groups become disconnected, and at the end of the fermentation the cells have quite separated from each other, not more than 2 or 3 per cent. remaining united, and even these in groups of not more than two cells together. This is represented in Fig. 39.