HEMIPTERA. 751 HEMP. hoppers (Membraeidie) have their fossil nnoes- lors in the Tertiary rocks. Some of the lleterop- tera, such as the water-bugs, appear in the Jurassic. Chinohbiigs, squash-bugs, and bedbugs appear in the Liassic and Tertiary. BiiiLioGRAPHY. Osborn, "Chissification of Heniiptera," in Entomologica Americana, vol. i. ( Brookljnj, 1885); Sharp, "Insects," in Cam- briilye ?iatural History, vols, v., vi. (London and New York, 1900) : Conistock, Manual for the fitudy of Insects (Ithaca, 1895); Howard, Tho Insect Book (New York, 1901). HEM'IRAMPH (from Gk. -ti/n-, U-mi-, half + pd/icpoi, rJiaiiiplios, snout) . A lish of the fam- ily llc'iiiiraiiipliidae. See Halfbeak. "hem'ISHEN. See Hemessen. HEM'LING, Haks. A Flemish painter, more correctly Memling (q.v. ). HEMLOCK (AS. hemlic, hymhlica: hem- liK'k ) , ConiuDi. A genus of plants of the nat- ural order Umbellifene, the members of which have compound umbels of small white ilowers, small involucres and involueels, the former con- sisting of several small leaflets, the latter of three leaflets all on one side; the limb of the ealy.K merely rudimentar}', and a compressed ovate fruit with five prominent wavy ridges and no vittie. The best known and only important species is the common or poison hemlock (Co- niitm maculatum) , which grows by waysides on lieaps of rubbish, and in other similar situations throughout Europe, in some parts of Asia, and naturalized in North America and Chile. It has a root somewhat resembling a small parsnip; a round, branched, hollow, bright-green stem, two to seven feet high, generally spotted with dark )nirple; large tripinnate, dark shining green leaves with lanceolate pinnatifid leaflets. All parts of the plant are destitute of hairs. The whole plant has a nauseous smell, particularly if rubbed or bruised. The leaves and fruits are employed in medicine. The leaves should be gathered just before the time or at the com- mencement of flowering, and after the removal of the larger stalks they should be quickly dried by a heat not exceeding 120°. As, however, they sometimes j'ield little or none of the active prin- ciples in the plant, the fresh leaves are pre- ferred. The whole plant contains the active principles, and many fatal cases of poisoning have been attributed to eating the roots under the mistaken idea that they were parsnips. The uses of hemlock in medicine are few and unimportant and depend chiefly upon its action upon the motor nerves, beginning with their end- organs. Although large doses cause complete paralysis by their action upon the peripheral nerves, sensation and consciousness are not af- fected; death finally occurs by extension of the paralysis to the muscles of respiration. In large or poisonous doses it sometimes gives rise to coma, and sometimes to convulsions or violent delirium. Among the ancient Greeks poisoning by hemlock was a common mode of death for condemned criminals, but whether it was the juice of the common hemlock or the water-hemlock that was used is tinknown. The strength of its preparations is very variable, as its active principles are volatile. Practicallythe only use of the drug is in tetanus, hydrophobia, strychnine poisoning, and other convulsive dis- orders. Even in these it is rarely used, and only to prevent exhaustion by lessening muscu- lar contractions. Water-hemlock, or cowbane {Cicuta i^irosa), is also an imbelliferous jilant, of a genus having vaulted umbels, a live-toothed calyx, and almost globose fruit, each carpel with five broad flattened ribs and evident single vittiE. Water-hemlock grows in ditches, the margins of ponds, and wet grounds in Kuroi)e .md the north of Asia. It has a large fleshy while root, covered externally with fibres; an erect nuich- branehed stem, two to five feet high; tri]iinnate leaves, with linear-lanceolate regularly and sharply serrated leallels, one general involucre or only a single small leaflet, partial iiividucres of many short narrow leallets, and while flowers. It is a virulent narcotic acrid poison. Another Bpecies, Cicuta maculata, is common in North America, growing in many places. It has a spotted stem, like that of true hemlock, the name of which it very generally receives in North America. The leaves are tritemate, the leaflets ternate. It is a very poisonous ])lant, and is the cause of many deaths. Cicuta, in Latin, seems to have been the name of the same plant called eoncion by the Greeks, but it is not known whether this or the previous plant was so de- nominated. See CoNiiNE. HEMLOCK-TREE, or He Ji lock Sprcce. A name applied to the coniferous trees which be- long to the genus Tsuga, especially to Tsufia Cana- densis. This is a large, graceful tree with much the habit and appearance of some spruces. It is found from Nova Scotia to Alabama and Georgia, and west to Wisconsin and Jlinnesota. The leaves are one-half inch long, bright green above and silvery beneath. The cones, which have few thin bracts, are scarcely longer than the leaves. The wood, light, soft, brittle, and light-red in color, is extensively used in building. It warps badly when exposed. The bark is largely em- ployed in tanning leather, for which jiurpose it ia preferred and more extensively used than any other American product. Hemlock oil is distilled from the branches and leaves, and pitch is ob- tained from the trees. There are nimcrous culti- vated varieties which are very oriumicntal, espe- cially while the trees are young. Tstiya Caro- liiiiana is a second species, which occurs locally in Virginia, North Carolina, and Georgia. Other species are found in Asia. See SPRUCE. HEMP (AS. henep, OHG. Iwnaf, hanof, Ger. Hunf ; connected with Lat. cannabis, Gk. xivvapis, kannabis, OChurch Slav, konoplya, Lith. kana- pes, hemp, and probably with Skt. ^ana, hemp). Cannabis sativa. A fibre plant of the natural order Urticacese (q.v.), which has the male and female flowers on diflTcrent plants. There is only one known species of the genus, which varies con- siderably, however, in dill'erent soil, climate, and cultivation. It is an annual, a nalive of the warmer parts of Asia, but has been cultivated in Eiirope from the earliest historic times, and is now naturalized in many parts of Europe and America. Like flax, it adapts itself to diversities of climate, and is cultivated equally well under the burning sun of the tropics, and in the north- ern parts of Russia. It is, however, readily inJTired by frost, particularly when young; and in many countries where it is cultivated, it suc- ceeds only because the simmcr is sufficiently long for its whole life. Hemp varies very much in height, according to the soil and climate; some-
