_Gentian Root_; F. _Racine de Gentiane_; G. _Enzianwurzel_.
=Botanical Origin=—_Gentiana lutea_ L., a handsome perennial herb,
growing 3 feet high, indigenous to open grassy places on the mountains
of Middle and Southern Europe. It occurs in Portugal, Spain, the
Pyrenees, in the islands of Sardinia and Corsica, in the Apennines,
the mountains of Auvergne, the Jura, the Vosges, the Black Forest, and
throughout the chain of the Alps as far as Bosnia and the Danubian
Principalities. Among the mountains of Germany, it is found on the
Suabian Alps near Würzburg, and here and there in Thuringia, but not
further north, nor does it occur in the British Islands.
=History=—The name _Gentiana_ is said to be derived from Gentius, a
king of the Illyrians, living B.C. 180-167, by whom, according to both
Pliny and Dioscorides, the plant was noticed. Whether the species thus
named was _Gentiana lutea_ is doubtful. During the middle ages, gentian
was commonly employed for the cure of disease, and as an antidote to
poison. Tragus in 1552 mentions it as a means of diluting wounds, an
application which has been resorted to in modern medical practice.
=Description=—The plant has a cylindrical, fleshy, simple root, of pale
colour, occasionally almost as much as 4 feet in length by 1½ inches in
thickness, producing 1 to 4 aerial stems.
The dried root of commerce is in irregular, contorted pieces, several
inches in length, and ½ to 1 inch in thickness; the pieces are much
wrinkled longitudinally, and marked transversely, especially in their
upper portion, with numerous rings. Very often they are split to
facilitate drying. They are of a yellowish-brown; internally of a
more orange tint, spongy, with a peculiar, disagreeable, heavy odour,
and intensely bitter taste. The crown of the root, which is somewhat
thickened, is clothed with the scaly bases of leaves. The root is tough
and flexible,—brittle only immediately after drying. We found it to
lose in weight about 18 per cent.; by complete drying in a water-bath
it regained 16 per cent. by being afterwards exposed to the air.
[1614] _De la famille des Loganiacées_, 1856. 130.
[1615] _Therapeutics and Materia Medica_, Philadelphia, ii. (1868) 651.
=Microscopic Structure=—A transverse section shows the bark separated
by a dark cambial zone from the central column; the radial arrangement
of the tissues is only obvious in the latter part. In the bark,
liber-fibres are wanting; and in the centre there is no distinct
pith. The fibro-vascular bundles are devoid of thick-walled ligneous
prosenchyme; this may explain the consistence, and the short even
fracture of the root. It is moreover remarkable on account of the
absence both of starch and oxalate of calcium; the cells appear to
contain chiefly sugar and a little fat oil.
=Chemical Composition=—The bitter taste of gentian is due to a
substance called _Gentiopicrin_ or _Gentian-bitter_, C₂₀H₃₀O₁₂.
Several chemists, as Henry, Caventou, Trommsdorff, Leconte and Dulk
have described the bitter principle of gentian in an impure state,
under the name of _Gentianin_, but Kromayer in 1862 first obtained it
in a state of purity. Gentiopicrin is a neutral body crystallizing in
colourless needles, which readily dissolve in water. It is soluble
in spirit of wine, but in absolute alcohol only when aided by heat;
it does not dissolve in ether. A solution of caustic potash or soda
forms with it a yellow solution. Under the influence of a dilute
mineral acid, gentiopicrin is resolved into glucose, and an amorphous,
yellowish-brown, neutral substance, named _Gentiogenin_. Fresh gentian
roots yield somewhat more than ⅒ per cent. of gentiopicrin; from the
dried root it could not be obtained in a crystallized state. The
medicinal Tincture of Gentian, mixed with solution of caustic potash,
loses its bitterness in a few days, probably in consequence of the
destruction of the gentiopicrin.