THE BAKERS' GUIDE

and they are thus capable of vegetating with most extraordinary- rapidity.

The process of budding usually commences by a distortion of the cell at one side, which is followed by the cell-wall protruding > the protuberance, increasing in size, becomes more or less- rounded in shape; then a sort of strangulation process com* mences, which causes the cell-walls of the protuberance to meety and at last the bud becomes detached. Sometimes a cell gives- rise to several protuberances at once.

If we examine a speck of yeast under the microscope with a high magnifying power, we observe that certain of the cells are more or less elongated, while others are more nearly spherical in shape, and they are all isolated. In many of them there are apparently vacant spaces which are lighter or darker than the surrounding parts of the cell according as the object or the object-glass is slightly shifted. Granulations, too, are seen in the cells, and they present altogether a somewhat shrivelled appearance, or sometimes they string together like small sausages, cannibal-like living upon each other. Such cells are suffering from deficient nutrition and insufficiency of food y they are, in fact, half starved. If they be transferred to- some fresh wort, and placed in shallow vessels so that they are freely exposed to the air, their appearance will be greatly improved. They will be seen to have filled out and become fatter, while the vacuoles or vacant spaces have disappeared, the granulations are scarcely visible, and the distended cell* walls are difficult to see, they are nearly all budding, and the, buds are at different stages of development. The characters of the two conditions of yeast may be shortly summed up as follows :

Old Cells. — Isolation and granulation ; shrinking of the pro- toplasm to the cell-wall and creation of vacuoles ; shrivelled appearance.

Revived Cells. — Cells distended; appear transparent to a, greater degree ; budding and growth of buds until detachment y interior gelatinous matter contains fine granulations not easily, seen, but appearing brilliant at a certain distance.

Brewers are acquainted with two varieties of yeast and two. processes of fermentation, namely, that which occurs at a high temperature, and the yeast of which rises to the surface of the liquid, is called a " high fermentation " ; that which, on the contrary, is conducted at a low temperature, and the yeast of which is below the surface of the liquid, is called a " low fermentation." With all our brewers and distillers high fermentation is in universal favour,, it is so much more rapid in its action, and generally saves both time and space. To adopt the process of low fermentation in a