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So also the cambium tissue, which made very delicate cells and which usually white or colorless, readily oxidized and becomes darkened exposure air.
Nearly all barks, when first removed from the stems, branches or roots, are white their interior surfaces, but the oxidation after removal changes their colors those which are characteristic the commercial barks thus, cane! I a alba remains nearly white, slippery elm becomes pale brownish white, sassafras changes reddish or bright rust-brown, cinnamon brownish and old buckthorn bark almost blackish or purplish-brown, that the tints or colors tbe Interior surfaces barks become diagnostic value.
The appearance the outer surfaces not greatly altered except when the natural outer portions creative writing coursework ideas are removed and only the inner bark sent into trade when the outer surface differs from the natural appearance in the ungathered bark this the case, for instance, in Cassia and Ceylon cinnamons, in slippery elm, etc. which are described as inner As soon as a bark separated from the stem or root commences lose moisture, and in drying out necessarily shrinks.
The shrinkage will greatest in that part the bark which contains the softest cells, therefore more in the inner than in the outer portions. If the outer portions are removed, the shrinkage will even or nearly even from both surfaces and the pieces bark will remain more or less flat, as in slippery elm, but in some barks the flat pieces are in consequence pressure applied, as in the larger pieces yellow or red cinchona, especially as formerly brought from South America.
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As the softer and more succulent inner parts this bark lose their moisture, this generally causes the bark curl inward and according the degree curvature, different descriptive names are given the barks.
When the curvature slight, as in a the accompanying figures, the pieces are usually described as curved pieces, but as curvature may and often irregular, better restrict the term curved pieces bark irregular shapes and use the word troughs first proposed in this connection the author these notes in the Com paniox as a more convenient, expressive and descriptive word describe the pieces bark curved in the regular manner shown in the figure mentioned. If the bark rolled from one side into a tube or cylinder, this called a quill fast custom essays or aimple quill as, while if rolled inward from both sides called a double quill An unequal shrinking bast and medullary rays will cause longitudinal wrinkles the inner surfaces, if the cheap essay services external layers will not yield readily, as form quills drying, fissures will occur the inner surface the bark as already shown in a drawing the inner surface wild cherry bark or ridges may formed, as in atuus rubra, the reason for which will readily understood from an examination the following illustral ion. In some cases, as in cascarilla, the bark does not conditions present in different parts.
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In some other bitaof wood may adhere the shrinkage in all these cases will take place probably most in the middle bark and irregular torsion will exerted both inner and outer surface tissues, the result being pieces bark which are irregularly bent and twisted, and this kind pieces that would limit the term curved pieces, already referred It will readily seen that the main characteristics structure, which determine color and shape the pieces commercial barks are inherent attributes the plant from which each particular bark obtained, and that while the size the branch or stem best site to find essays or root from which the bark obtained must in a limited way have influence dissertation help literature review the shape owing more or less heavy layers outer bark mainly or the rapidity drying may some extent modify the tint the color, or the season the year at which the bark gathered may influence the bark in various ways essay review service and especially as regards its constituents, yet the essential characteristics which are pharmacognosy diagnostic value will necessarily present in each bark, no matter when or how gathered.
Various methods classification have been used, which those based structural features are course most desirable and exact but other classifications have also been used and well use them all in combination, as the barks present many difficulties in this regard.
The entire flower shown in the drawing in natural size the petals are very thin and delicate, help finishing thesis broadly oval, broader than long, dark-red, with a blue-blank spot at the base where tbey are inserted the receptacle hidden in the flower the stamens and pistil odor faintly narcotic, taste bitterish mucilaginous. In the drug the petals are much shrunken. A deep-red coloring principle, rhceadic acid, soluble in water and in dilute alcohol, etc. This group includes two drugs only these drugs consist the styles. and stigmas the plants from which they are derived, the stigmas being the important part in Crocus and the styles in Zea. The group called Sexual Organs some authors, but this evidently wrong because only parts, and not even the essential parts, only the female organs are present and moreover, there would just as much reason call Flores Verbasci Corollas with Sexual Parts as call these drugs Sexual parts. The group has also been called Styles with Stigmas, but as in the Latin titles for these drugs, as used in different works, the word Stigmata has long been used, deemed inadvisable change the custom, and this word therefore preferred as the most appropriate title for this group drugs. Separate stigmas, or three attached a style, linear tubular, long, Asia Minor and in Southern Europe most the saffron sold in this country from Spain and France. The illustration shows the stigmas i a natural size, with a short piece the style attached, but in the drug they are crumpled and shrunken also, the left, the end enlarged and the right a portion the margin, very much magnified. To examine the drug, drop a few shreds warm water, when will regain its fresh form. The stigmas are usually gathered that a small portion the style remains attached, and the three stigmas a flower thereby remain attached in the drawing bat occasionally they are saffron a rich orangebrown color with reddish not dry and hard, with a peculiar strong odor and an aromatic bitterish taste, and when chewed stains the saliva a deep golden yellow. Coloring matter, gam, wax, etc. Seldom employed otherwise than as a coloring agent.