Microscopic Structure—A transverse section of this rhizome shows two different portions of tissue, separated by the so-called nucleus-sheath. The latter consists of an unbroken ring of prismatic cells, analogous to those occurring in sarsaparilla. In Rhizoma Graminis, the outer part of the tissue exhibits a diffuse circle of about 20 liber bundles, and the interior part about the same number of fibro-vascular bundles more densely packed. The pith is reduced to a few rows of cells, the rhizome being always hollow, except at the nodes. No solid contents are to be met with in the tissue.
Chemical Composition—The constituents of couch-grass include no substance to which medicinal powers can be ascribed. The juice of the rhizome afforded to H. Müller[2722] about 3 per cent. of sugar, and 7 to 8 per cent. of Triticin, C₁₂H₂₂O₁₁, a tasteless, amorphous, gummy substance, easily transformed into sugar if its concentrated solution is kept for a short time at 110°C. When treated with nitric acid, it yields oxalic acid. The rhizome affords also another gummy matter containing nitrogen, and quickly undergoing decomposition; the drug moreover is somewhat rich in acid malates. Mannite is probably occasionally present as in taraxacum ([p. 394]), for such is the inference we draw from the opposite results obtained by Stenhouse and by Völcker. Starch, pectin and resin are wanting. The rhizome leaves 4½ per cent. of ash.
Uses—A decoction of the rhizome has of late been recommended in mucous discharge from the bladder.
Substitutes—Agropyrum acutum R. et S., A. pungens R. et S., and A. junceum P. Beauv., by some botanists regarded as mere maritime varieties of A. repens, have rootstocks perfectly similar to this latter.
Cynodon Dactylon Pers., a grass very common in the South of Europe and the warmer parts of Western Europe, also indigenous to Northern Africa as far as Sennaar and Abyssinia, affords the Gros Chiendent or Chiendent pied-de-poule of the French. It is a rhizome differing from that of couch-grass in being a little stouter. Under the microscope it displays an entirely different structure, inasmuch as it contains a large number of much stronger fibro-vascular bundles, and a cellular tissue loaded with starch, and is therefore in appearance much more woody. It thus approximates to the rhizome of Carex arenaria L., which is as much used in Germany as that of Cynodon in Southern Europe. The latter appears to contain Asparagin (the Cynodin of Semmola[2723]), or a substance similar to it.
II.—CRYPTOGAMOUS or FLOWERLESS PLANTS.
Vascular Cryptogams.
LYCOPODIACEÆ.
SPORÆ LYCOPODII.
Lycopodium; Semen vel Sporulæ Lycopodii; F. Lycopode; G. Bärlappsamen, Hexenmehl.