This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Lettuce: a plant with slender but firm stalks, which yield, as do the leaves, a milky juice on being wounded: the flower consists of a number of flat slosculi set in a small scaly cup, followed by short flat seeds, which are pointed at both ends and winged with down.
I. Lactuca Jativa C. B. & Linn. Garden lettuce: with oblong, broad, rounded, uncut leaves; and numerous flowers (landing on long pedicles in the form of an umbel. It is annual, and raifed at different times of the year in culinary gardens.
The young leaves of the several species or varieties of garden lettuce are emollient, cooling, in some small degree laxative and aperient, easy of digestion, but of little nourishment; salubrious in hot, bilious, indispositions; less proper in cold phlegmatic temperaments. In some cases, they tend to procure sleep; not as being possessed of any strictly hypnotic power; but by virtue of their refrigerating and demulcent quality. When the plant is grown up, it proves considerably bitter, though less so than most of the others of the lactescent kind, to which it is similar in its general virtues.
The seeds, which in the common lettuce are of a grey or ash colour, in the cabbage lettuce black, unite with water, by trituration, into an emulsion or milky liquor, which has nothing of the aperient bitterness of the milky juice of the leaves, and is nearly similar to the emulsions made with almonds. The lettuce emulsions have been supposed to be more refrigerant than those of the almond, and hence have sometimes been preferred in heat of urine and other dif-orders from acrimony or irritation.
2. Lactuca silvestris Medicorum. Lac-tucdsilvestris &Scariola Pharm. Paris. Lactuca silvestris costa spnosa C. B. Lactuca Scariola Linn. Wild lettuce: with the leaves cut almost: to the rib into indented triangular segments; and the stalks and the ribs prickly. It is biennial, grows wild in hedges, and flowers in June.
This species is considerably bitterer than the garden lettuces, and more aperient and laxative. It is nearly similar, in virtue as in taste, to endive unblanched.
3. Lactuca graveolens: lactuca silvestris odore virofo C. B. Lactuca virofa Linn. Strong scented lettuce, by some erroneously supposed to be the wild lettuce of medical writers: with the lower leaves entire, the upper jagged, the stalks and leaves prickly. It is biennial, found in hedges and by the sides of ditches, and flowers in June.
This species differs greatly in quality from the two preceding, though reckoned by botanists to be only a variety of the second. It smells slrongly of opium, and appears to partake, in no small degree, of the virtues (a) of that narcotic drug. The opiate power of the lettuce, like that of the poppy-heads, resides in its milky juice, but whether the milk of the lettuce is of equal safety, or its virtue precisely of the same kind, with that of the poppy, is not known.
* Dr. Collin of Vienna has written a tract recommending the use of this plant in the cure of dropsies. The preparation he employs, is an extract from the expressed juice, first suffici-ently clarified, and evaporated by a very gentle heat. He begins with small doses; but in dropsies of long standing, originating from visceral obstruclions, he rises to the quantity of from one to three drams in twenty-four hours. He has constantly found it a mild remedy, agreeing perfectly with the stomach. It usually kept the body open, but without exciting a purging. It seldom failed of proving powerfully diuretic, and at the same time mildly diaphoretic. The patient's thirst is said to have been totally extinguished by its use; but at the same time we are told that they were allowed to drink freely of diluting liquors during the course. Dr. Collin asserts, that out of twenty-four dropsical cases, all but one were cured by the use of this medicine; a degree of success that certainly entitles it to the further notice of the faculty.
(a) Ray, Historia plantarum, i. 222. Boerhaave, Hist. bort. Lugd. Bat. p. 127.