The carefully dried leaves, with not more than 2 p. c. of stems, flowers, foreign matter.
Syn. Digit., Foxglove, American or Purple Foxglove, Fairy Gloves, Folks' or Ladies' Glove, Dog's Finger, Fairy Fingers, Dead Men's Bells, Finger Flower, Thimbles, Fairy Cap, Lion's Mouth, Scotch Mercury, Throatwort, Rabbit's flower; Br. Digitalis Folia; Fr. Feuilles de Digitale pourpree (de grande Digitale), Doigtier; Ger. Fingerhutblatter.
Dig-i-ta'lis. L. pertaining to the fingers, fr. digitus, a finger - i. e., the finger-shaped corolla, named by Fuchs, 1542, after Ger. fingerhut, a thimble.
Pur-pu're-a. L. purpureas, purple-colored - i. e., its purple flowers.
Foxglove. Corruption of Folks' glove, Folk, synonym of Fairies.
PLANT. - Biennial or perennial, succulent, downy, leafy herb, ,6 1.5 M. (2-5°) high; flowers July-Aug., tubular, campanulate, 5-lobed, outside purple, inside dark-spotted upon a white ground, mouth hairy, terminal, 1-sided racemes; one variety with white Bowers; fruit 2-celled pyramidal capsule; seeds many, small, brownish-gray. Leaves, more or less crumpled and broken, 10-30 Cm. (4-12') long, 5-15 Cm. (2-6') broad, ovate, abruptly contracted into winged petiole, 5-10 Cm. (2-4') long, or in the smaller leaves nearly absent, crenate, irregular, thin; dull green, wrinkled, sparsely hairy above; pale green, gray, densely pubescent below; venation conspicuously reticulated, midrib and principle veins broad and flat, often purplish, lower veins continued into the wings of the petiole; odor slight, characteristic; taste strongly bitter. Powder, dark green; microscopically - many fragments of non-glandular, 2-8-celled hairs, few glandular hairs with 1-2-celled stalk and head, numerous fragments of lamina with sto-mata, water-pores, fibro-vascular tissues. Should be kept dark, in tightly-closed containers. Solvents: alcohol (65 p. c.); boiling water partially. Dose, gr. 1-2 (.06-. 13 Gm.).
Adulterations. - Leaves: First year's leaves - radical, with very long petioles; also leaves of D. ambig'ua (ochroleu'ca) - nearly smooth; Verbascum Thapsus - yellowish-white, entire, densely long-tomentose, mucilaginous; Sym'phytnm officinale - entire, scabrous; Cony'za (Inula) squarrosa - scabrous, entire; Powder: Distinguished from all adulterations by the 2-8-celled hairs and absence of calcium oxalate crystals.
Fig. 362. - Digitalis purpurea.
Fig. 363. - Digitalis purpurea: a, single flower; b, the same opened.
Commercial. - Plant cultivated for ornament and medicine, producing the first year a large fleshy root and a rosette of radical leaves, but no flowering and fruiting stem until the second year. Leaves should be collected from wild plants growing in mountainous regions when two-thirds of the flowers are expanded, July-Sept., from the fact that two series of compounds are formed in plants by the action of light and air: 1, nutritions, those for nutrition (constructive metabolism); 2, secretions, or secretions of waste products (destructive metabolism). It is only during the flowering stage that every nutritive avenue and substance is taxed and used for flower perfection, thereby leaving elsewhere, as in leaves, etc., the waste products, alkaloids, etc., in a most concentrated form; for the same reason belladonna, hyoscyamus, and many other plants should have leaves (all official parts) gathered when in bloom - the second year of growth, hence the second crop of leaves. Only those full grown and fresh are collected, then carefully and quickly dried without exposure to sun or undue heat, and protected from external moisture, each being placed separate,
Fig. 364. - Digitalis leaves, upper surface: a, of the first year's growth; b, of the second year's growth.
or in baskets, in dark drying stoves; or the entire plant may be hung up by the roots in a current of warm air, such yielding most digitoxin, that by which the drug's value is determined; carelessness in this process often renders the product inert. When dry should be kept in air-tight, dark containers (or tins, over lime - old Dutch method), and not longer than 1 year if exposed to light and moisture, as quality depends upon color, smell, taste, and yield of digitoxin; seeds are much stronger, keep better, and do not deteriorate upon drying; lose on drying 75 p. c.; cultivated leaves are thicker, deeper color, less hairy, active and acute.
Constituents. - Digitoxin, Digitophyllin, Gitalin (digitalein, dig-alen), gitin, digitsaponin (digitalin + saponin), enzymes, manganese, volatile oil, fixed oil 5 p. c, gum, starch, sugar, chlorophyll, inosit, pectin, coloring matter (red, yellow), digitalosmin, antirrhinic acid, digitalic (malic) acid, ash 15 p. c.
Digitoxin, Digitophyllin, Gitalin (digitalin-group). - Heart stimulant glucosides, the two former soluble in alcohol, the latter also in water, which alone occurs (+ digitsaponin) in the infusion, making it possibly the most important content.
Gitin, Digitsaponin (saponin-group). - Inactive, but presence may increase the activity of the glucosides.
Enzymes (oxydases - only in fresh leaves). - Oxidize or hydrolyze, the glucosides (digitoxin, digitophyllin, gitalin) into glucose, digitoxi-genin and digitaligenin - all inactive, the associated manganese aiding in the decomposition - this latter being averted only by quickly drying fresh leaves and keeping them dry.