Thus then we see—and several other examples throughout this work confirm the fact—that saccharine liquids holding mineral salts in solution are as capable of complete fermentation as any media of natural composition. It is true that ferment develops slowly and with difficulty in them, and at times takes on rather curious forms, but, nevertheless, it does develop in the media and carry on a fermentation in which not the minutest particle of sugar is left undecomposed. This is true, at least, in the case of _saccharomyces pastorianus_, but there are other ferments which in such media are checked in their multiplication and in their continued action on sugar. One condition indispensable to the accomplishment of fermentation in such a sweetened mineral medium, by means of _saccharomyces pastorianus_, is the absolute purity of the materials and of the ferment. It is necessary that the life and physiological action of the latter should be in no way interfered with by the presence of other microscopic organisms. We shall have occasion to revert to this important detail in connection with our growths. [Illustration: Fig. 49.] Fig. 49 represents the ferment as it appeared when examined on August 11th, 1873. We can no longer recognize in it any _saccharomyces pastorianus_. The general appearance is spherical, and there are a number of clusters of budding cells which remind one at first sight of the mode of germination of brewers’ “high” yeast. At _a_, _a_, _a_, we see globules from which irregular abortive filaments have sprung, a proof of difficult germination. No such monstrosities could ever have occurred if we had used beer-wort or must as our nutritive medium.