Mr. A. S. Taylor, in his work on Poisons, says, "It varies much in strength. Wibmer found that two 
grains caused headache and somnolency, (Op. cit. 200.) By the smell only, it is liable to be mistaken for opium. 
It is but little soluble in water, and after long boiling, it forms a brown turbid solution which gives a greenish 
tint with sesquichloride of iron. It therefore contains no meconic acid. On examining a good specimen I have 
not found any trace of morphia. This shows that the odour of opium may exist in substances which do not 
contain meconate of morphia. Nitric acid gives a yellowish tinge to the decoction, as it does to most other 
vegetable solutions. It is bitter to the taste, which appears to be owing to the presence of a bitter principle 
called lactucin, upon which its feeble narcotic properties probably depend. There are no tests for lactucarium 
further than the colour, the opiate odour with the want of solubility, and the absence of the other chemical 
characters of opium. In the plant, it is combined with malic acid, potash, and resin. (Fisher, loc. cit.)” 
LACTUCA S ATI VA.— GARDEN LETTUCE. 
Spec. Char. Leaves rounded ; stem-leaves heart-shaped ; stem terminating in a corymbiform panicle. 
The original country of the Garden Lettuce is unknown. By some it is supposed to be an accidental 
variety sprung from some other species of Lactuca. It was cultivated in England, by Turner, in 1562, 
and probably much earlier. The leaves are large, milky, frequently wrinkled, usually pale green, but varying 
much in form and colour in the different varieties. The radical leaves are roundish, and toothed at the 
margin ; those of the stem are obovate or heart-shaped. The stem is round, leafy, two or three feet high, 
and corymbiform at the top, with numerous bright yellow flowers, which appear in July. 
The Garden Lettuce contains, like the other species, a quantity of milky juice ; having when inspissated 
the dark colour, and, in some degree, the odour and taste of opium. The inspissated juice was found by 
Professor Pfaff to consist of 41 parts soluble in water, 7 of wax, 6 of resin, 18 caoutchouc, and 8 of loss = 
80. It contains a free acid, analogous to the oxalic, but different, and a narcotic principle ; but no morphia. 
The Lettuce is universally esteemed as a cooling and agreeable sallad ; and the expressed juice has been 
long known to possess considerable narcotic powers. Celsus says "Somno vero aptum est lactuca, max- 
imaque aestiva, cujus cauliculus jam lacte repletus est.” (Dr. Med. ii. xxxii.) The spirituous extract, under 
the title of lactucarium, has been strongly recommended by the late Dr. Duncan, in doses of from two to 
six grains, as a substitute for opium, in pulmonary consumption, and some other diseases. 
Both the species of lettuce above described afford the lactucarium, which however, as now prepared, is 
not the spirituous extract but the inspissated proper juice alone ; and hence differs materially from the 
tkrydacd of the continental physicians, which is formed by the expression of all the juices, both the crude 
and elaborated saps combined with all the other secretions of the plant which pressure can force out. The 
true lactucarium is obtained by wounding the plants in the flowering season when their vessels are filled 
to repletion with proper juice, and so irritable that they often spontaneously burst or are ruptured by very 
slight accidental injuries. If at this season transverse scratches, or slight incisions be made through the 
teguments of the stems, the milky juices exude, and soon become in a slight degree inspissated, when the 
exudations should be scraped off with a silver spatula, and evaporated to a proper consistence at the ordinary 
atmospheric temperature; or if artificial heat be applied, it should not exceed 120° of Fahrenheit’s scale. 
The soporific effects of lettuce have long been noticed and familiarly known : the poets feigned Venus, 
after the death of Adonis, to have sought a bed of lettuces to soothe her grief. And Galen, who, when old, 
suffered much from watchfulness, found great relief from eating a lettuce at night; a practice which is com- 
monly resorted to, with the same effect, by wakeful persons in the present day. 
In the type Cichoraceee, of the Compositee where the lactucae are found, a narcotic principle more or 
less prevails along with the bitter one of the allied type Cynaracese, or Cynarocephalae, and which gives way 
in the third group the Corymbiaceae, or Sorymbiferae, to an aromatic and stomachic principle, as in the 
chamomile and tansy. By cultivation, especially by exclusion from light, these narcotic and bitter principles 
are regulated and modified in their developement, sometimes being increased, and sometimes lessened, 
according to the purpose for which the plants are intended to be used. By exclusion from light, the sap 
becomes only in part elaborated, and the taste and effects of the plants ameliorated, as is the case in the 
cultivated lettuces, endives, &c. And hence it is, that the cultivated lactuca sativa has not only a much less 
nauseous flavour, but also affords much less lactucarium than the uncultivated lettuce, and especially than the 
lactuca virosa, as shown by the comparative experiments of Schutz, who from two plants of equal weights found 
56 grains of dry lactucarium were afforded by the lactuca virosa, while from the lactuca sativa he only 
procured 17 . 
Besides the lactuca sativa, which is our common garden lettuce, the French cultivate as dietetic plants, 
the palmate, the oak, and the endive leaved species ; (lactuca palmata, quercina, and intybacea ;) all of 
which, however, as well as our lactuca sativa are believed by many botanists not to be distinct species, but 
only permanent varieties of the lactuca virosa, which is esteemed the parent or original form of all. 
Lettuces, unlike many other vegetables, such as the cabbage, the spinach, &c., can be grown to as great 
perfection in a warm as in a temperate climate, provided they be grown on rich soil, and abundantly supplied 
with water. Hence, says Loudon, the lettuces of Paris, Rome, and Calcutta, are as large and tender as 
those of London and Amsterdam. 
