American journal of pharmacy . bservable in fresh fractures or cuts. If such a surfacebe moistened, thouf^h, the white is observed to turn a light, brightyellow, and the former yellow to a striking dull orange color, thusdarkening the whole effect. Somewhat the same thing happens byexposure to the air. An observation of a freshly-cut and moistenedsurface shows that the tissues in numerous places are aggregatedinto contorted groups, to which effect the mottled or marbledappearance is due. Thin sections show that the lighter ground-work tissue is composed of thin-walled parenchyma cells, while t
American journal of pharmacy . bservable in fresh fractures or cuts. If such a surfacebe moistened, thouf^h, the white is observed to turn a light, brightyellow, and the former yellow to a striking dull orange color, thusdarkening the whole effect. Somewhat the same thing happens byexposure to the air. An observation of a freshly-cut and moistenedsurface shows that the tissues in numerous places are aggregatedinto contorted groups, to which effect the mottled or marbledappearance is due. Thin sections show that the lighter ground-work tissue is composed of thin-walled parenchyma cells, while thedark and contorted areas are principally fibro-vascular tissue. Thelatter, in certain forms of the drug, is regularly arranged into spotshaving a radiate structure and forming the so-called stellate spots or Maseru of the Germans. Recent writers state that these areparticularly characteristic of the Russian variety, which is no longeron the market. The accompanying drawing (^Fig. ^), adapted fromBerg, illustrates the Fig. 4.—Cross-section of Rheum, after Berg. This peculiar structure is due to the method of growth, wherebythe numerous rudimentary leaves on the surface of the rhizomeleave the form of their fibro-vascular growth as a permanent recordon the parent stem. In the specimens examined this structure didnot make its appearance, and I think it will be found that, in itstypical form, it rarely does. What really was found was a massed 133 The Rhubarbs and a Probable Adulterant. {^Mih,iir irreo[ularity of the hbro-vascular tissue in certain areas, as shown inthe half-tone reproduction of a photomicrograph {^Frontispiece, ). This doubtless corresponds to the stellate structures of theRussian, but it is not carried out to the same extent. The Rhaponticuni {^Frontispiece, Fig. j) in the particular just men-tioned, presents an entirely different aspect, as is easily distin-guished from either variety of the Chinese rhubarb. There is adistinct and plainly-marked
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