"Cook, we are out of yeast; I wish you would make some".

Cook. "I never makes yeast; I always buys it".

Lady. "Yes, but it is too far to send to town for a pennith of yeast! How do you make yeast?"

Cook. "Well, I mixes flour, salt, and hop-water, and adds a pennith of yeast".

The poor lady is not able to discover how this will originate what is so indispensable, and hastens to the nearest neighbor with the question: " How do you make yeast?" Answer as before. "Mix flour, salt, and hop-water, and add a pennith of yeast." This reply any lady who chooses to make the experiment will receive every time she asks, whether from neighbor, baker, or any one else. Let her try a scientific friend, and more probably than not the same will be the result, and she is sorely puttied to know how it would be, if by any bad luck the whole country was to lose the source whence comes that important pennith!

So she inquires of everybody, gently insinuating that she wants the pennith left out in the answer; but, getting no satisfaction, she recollects that we discovered the vinegar plant, and she drove over to us. All our books were silent on the subject, so we applied to a learned botanist, who never allows anything that can be known to escape him, and here is his satisfactory elucidation of the mystery: -

Diastase is a peculiar nitrogenous substance, possessing the property of converting a large proportion of fecula into dextrin, and is found in the germ of the cerealia and tuber-cular vegetables; it appears to be formed at the moment of germination, at the expense of the albuminous matter contained in the grain, as it resides in the very origin of the germ, and, in the eye of the tuber; it is generally extracted from barley, which has sprouted by digesting the grain in water; it is applied in the arts for the purpose of obtaining dextrin, which is used in baking of pastry, and the manufacture of beer, etc. In the solution of sugar with albuminous substances, either vegetable or animal, after some time the solution becomes cloudy, and small, oval bodies are deposited, gradually increasing in sice until they attain a visible diameter; during the first two hours, the globule exhibits nothing peculiar, but, after this period, there forms at the point of the globule a rupture - a second globule - which gradually increases until it has obtained the dimensions of the original; this second globule soon generates a third, which is attached to the side of the second, in the same way as this grew on the first, and so on, and this is the way the yeast plant grows.

This plant is a species of microscopic vegetable, which is spontaneously developed in the organs of plants, and in a large number of nitrogenous substances, when left to putrefy, and is also formed by exposing to the ordinary temperature a solution of sugar mixed with albuminous substances, of vegetable or animal origin, as decayed cheese, spoiled meat, etc. It will hence be seen, that on adding an albuminous substance to a mixture of sugar and ferment, the sugar is not alone affected by the ferment, as the albuminous matter itself undergoes several metamorphoses, and is converted into yeast, which fact explains the reason why, in breweries, at the close of the operation, a quantity of yeast is made eight or ten times greater than that which had been originally used.

Raspail, in his Philosophy, says: "Starch consists of vesicles inclosing within them a fluid resembling gum; starch may be put into cold water without being dissolved; but when placed in hot water, these vesicles burst, and allow the escape of the liquid. This liquid is the dextrin of Biot, so called because it possesses the property of turning the plane of the polarization of light to the right hand." The way the pastry-cooks get it is, by putting starch in hot water. To which it may be added, that the credit of establishing the true nature and properties of the yeast plant is due to Caynard Latour, who, some years ago, proved that the conversion of sugar into alcohol and carbonic acid was caused by the presence and growth of the Torula cerevisiae, a cryptogamio plant, existing only in the form of globules, and Blondeau subsequently has thus described the nature of yeast: "There are two species of germs present in yeast, those of the Torula cerevisiae, and those of the Penicillium glaucum; the germs of the first (the true yeast plant) multiply with great rapidity, but never form stems, or deviate from the globular condition; the Penicillium glaucum also multiply, first in globules, but they soon extend themselves, unite, and form an arborescent vegetation, and are so much smaller than those of Torula cerevisiae, that they can be readily separated by filtration.

Perfectly developed stems of Penicillium glaucum always form on yeast when exposed for a length of time to the air, and always lose their property of fermentation when exposed to a heat of 212° Fahrenheit; the plant being killed by that temperature; the most favorable temperature is from 68° to 73°. It is now positively ascertained that the yeast globule (Torula cerevisiae) is a plant possessing a cellular structure, consisting of an external envelop resembling lignin, and of an azotized internal substance. - •

C. J. WlSTER.