THE YEAST PLANT. 



So she inquires of everybody, gently insinuating that she wants the pennith left out in tlio 

 answer; but, getting no satisfaction, she recollects that we discovered tho 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 anytliing that can be known to escape liim, and hero is his 

 satisfactory elucidation of tho mystery: — 



Diastase is a peculiar nitrogenous substance, iwssessing 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 

 tho albuminous matter contained in the grain, as it resides in the very origin of tho 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 tho pui-poso of obtaining dextrin, 

 which is used in baking of pastry, and the manufacture of beer, &c. In tho 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 size 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, &c. 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 meta- 

 morphoses, 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 lased. 



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 toCaynard 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 cerevisiie, a cryptogamic 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 genus of the first (the true yeast plant) multii)ly with great rapidity, but 

 never form stems, or deviate from tho globular condition ; tho 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 cerevisise, 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 fermen- 

 tation when exposed to a heat of 212=" Fahrenheit ; the plant being killed by that tempera- 

 ture ; the most favorable temperature is from 68° to 73°. It is now positively ascertained 

 that the yeast globule (Torula cerevisise) is a plant possessing a cellular structure, consist- 

 an external envelop resembling lignin, and of an azotized internal substance 



WlSTEK. 



