THE COMMON OAT.

589

from must ( mustum ) and wort during fermentation, partly as a scum, partly as a sedi-ment. Examined by a miscroscope it is found to be composed of minute vesicles, con-taining globules. MM. Cagniard Latour , and Turpin ( Biblioth. Univ. de Geneve,Nov. 1838) regard these vesicles as seeds (spores?), to whose germination the pheno-mena of fermentation are owing; for when they are placed in a saccharine fluid they ger-minate and produce little plants, which Turpin has denominated Torula Cerevisice (Nat.Ord. Futlgi, Subd. Mucedines). The growth takes place at the expense of the sugar,"liicli is partly converted into alcohol, while the plant gives out carbonic acid. Turpindetected these vesicles also in the cellular tissue under the envelope of the grain ofbarley. The remarkable and peculiar property possessed by yeast of exciting thev >nousJfermentation depends, according to the above authorities, on the vital properties?f the microscopic vegetables of which it is composed. When boiled in water its vitalityls destroyed, and in consequence it no longer retains the power of exciting fermentation.Considered in achemical point of view, yeast possesses many of the properties of gluten.

Yeast has been administered internally as a tonic and antiseptic in typhoid fevers.Cr. Stoker (On Continued Fever, p. 121, t)ubl. 1829-30) states, that it usually acts as amild laxative, improves the condition of the alvine evacuations, and is more effectualm removing petechia; and black tongue than any other remedy. It is admissible wheremnchona and wine cannot be employed, on account of the inflammatory symptoms.*he dose of it is two table-spoonfuls every third hour, with an equal quantity of cam-phor mixture. Enemata of yeast and asafcetida are said, by the same writer, to beefficacious against typhoid tympany.

- Externally yeast is employed in the form of poultice. The Cat a plasm a Fermesti,L & D. is prepared by mixing one pound of wbeaten flour with half a pint of yeast.Expose the mixture to a gentle heat until it begins to rise. It is applied to foetid ands j°Ughing sores as an antiseptic and stimulant: it destroys the fetor, often checks thesloughing, and assists the separation of the dead part. I have frequently heardlmtieuts complain of the great pain it causes. The carbonic acid is supposed to he theact ive ingredient.

A poultice composed of the grounds of stale beer, and equal parts of oatmeal and lin-meal, is sometimes substituted for the yeast poultice. Its effects are analogous to” e latter.

Fig. 91.

Ave'na sati'va, Linn. L. E. D.— The Common Oat.

Sex. Syst. Triandria, Digynia.

^itiina integumentis nudata, /*. Semina Avenae sativac: Semina decorticata ; Farina Avenae sativse exseminibus, E. Farina ex seminibus, D.)

History. —The oat is not mentioned in the Old Testament . Theo­ phrastus , Dioscorides , and Pliny , speak of it.

Hotany. Gen. Char. — Spikelets three, many flowered; flowers

remote ; the upper one withered. Glumestwo, thin, membranous, awnless. Palecetwo, herbaceous; the lower one awnedon the back, above the base, at thepoint almost bi cuspidate; the upper onebicarinate, awnless; awn twisted. Sta-mina three. Ovarium somewhat pyri-form, hairy at the point. Stigmata two,sessile, distant, villoso-plumose; withsimple hairs. Scales two, smooth, usu-ally two-cleft, large. Caryopsis long,slightly terete, internally marked by alongitudinal furrow, hairy at the point,covered by the palea;, adherent to theupper one (?) ( Kunth ).

Sp. Char .— Panicle equal. Spikeletstwo-flowered. Florets smaller than thecalyx, naked at the base, alternatelyawned. Root fibrous, annual [Kunth).

Arena sativa.

a - The white oat.h. The Siberian orTartarian oat.