Page:A Practical Treatise on Brewing (4th ed.).djvu/110

94 precipitates has suggested to several physiologists very singular views with regard to the nature of vegetation. When yeast of beer, or of wine diluted with water, is examined under the microscope, flattened and diaphanous globules are detected, which are frequently united in groups, and present an appearance of vegetation; others possess the aspect of certain infusoria.

“It would certainly be a very extraordinary phenomenon, if gluten and albumen, which have never been observed in the crystalline state, could assume a geometrical form in the process of the fermentation of wort of malt and vegetable juices. But this does not take place; these substances, on the contrary, separate in the same manner as all those which do not present a crystalline texture in the form of globules, swimming separately, or attached to each other.

“The appearance which they assume, in this instance, has induced certain philosophers to believe that they saw in yeast living organized beings, plants or animalcules, which, for food, assimilate the elements of sugar, and restore it as excretions, in the form of carbonic acid or alcohol. In this manner they explain the decomposition of sugar, and the augmentation of the mass of yeast in the fermentation of malt liquor.

“But this hypothesis destroys itself. In a pure aqueous solution of sugar, the so-called seed