The crab, (Cancer 1674 from rough, because of the roughness and sharpness of its claws. Cancer in Latin corresponds with the or the of the Greeks, and to the crab in the


Cancer marinus, (from mare, the sea). Is that called the sea crab; named also pagurus, cancer mae-nax Lin.

Cancer fluviatilis, (from fluvius, a river). The river crab, or cray fish; cammarus and gammarus; cancer astacus Lin. See Astacus marinus.

The black tips of the claw of sea crabs are levigated and used as an absorbent under the name of pulv. e. chel. cancrorum ppt. The London college direct a compound powder, made with crabs' claws, red coral, and chalk; but they all consist of the same calcareous animal earth.

Pulvis e chelis cancrorum compositus, is made by uniting a pound of the tips of crabs' claws prepared to three ounces of chalk, and as much red coral.

The composition has been considered to be inelegant, for the chelae cancrorum consists of a calcareous earth, part of which is combined with the phosphoric acid and glutinous matter; the corallium rubrum contains the same, and these are mixed with chalk, a somewhat more pure calcareous earth. The preparation is therefore far from a pure absorbent. The creta and testae ostreorum will better supp!y the place; and if calcareous earth is desired to be combined with phosphoric acid, it may be found in the cornu cervi ustum. Observations on the Sp. Alterum Pharmacop. Londincn-sis, 1788.

The college of Edinburgh in a former edition directed the following preparation called pulvis testaceus compositus.

Take of oyster shells prepared, one pound; and of white chalk prepared, half a pound. Mix.

The use of all the absorbent earths, and preparations of shells, is to absorb acidities in the primae viae; and this prescription from the Edinburgh dispensatory is equally valuable as a medicine with any other preparation of the kind, however attended with pompous epithets. If they meet with no acid to dissolve them, they should be accompanied by gentle purges. They are suspected of promoting putrefaction, but produce this effect only by absorbing acid, as we have already explained. If oyster shells form with a very weak acid a mucilage, like that which lines the inner surface of the stomach, bladder, and blood vessels, this mucilage may supply in some measure the want of the natural mucus when abraded.

See Lewis's Materia Medica, and Neumann's Chemical Works.

Cancer, (from Cancer 1679 a crab). By the term cancer, the Roman writers understood what the Greeks called gangrene and sphacelus; but the disease which is now called cancer is what the Greeks and Romans meant by carcinoma and carcinos. It is called also lu-flus, because it eats away the flesh like a wolf. See Celsus, lib. v. cap. xxviii.

Galen observes, that, as the crab is furnished with claws on both sides of its body, so in the carcinoma, or carcinos, the veins, which are extended from the tumour, represent with it a figure like a crab; hence is the disease called cancer. Boerhaave adds, that if the stagnating matter of a scirrhus is put in motion, so as to inflame the vessels situated in its margin, it becomes malignant, and then is called a cancer.

With Hippocrates we may, perhaps, most properly consider all the species as comprised in the occult and open cancer. A cancer then is, according to P. AEgi-neta, a hard unequal tumour, with or without an ulcer. Hippocrates calls that an occult cancer that is not yet burst; and that an open one which is ulcerated.

Mr. Pearson says, when a malignant scirrhus, or a warty excrescence, hath proceeded to a period of ulceration, attended with a constant sense of ardent and occasionally shooting pains, is irregular in its figure, and presents an unequal surface; if it discharges sordid, sanious, or fetid matter; if the edges of the sore be thick, indurated, and often exquisitely painful, sometimes inverted, at other times retorted, and exhibit a serrated appearance; and should the ulcer in its progress be frequently attended with haemorrhage, in consequence of the erosion of blood vessels; there will be little hazard of mistake in calling it a cancerous ulcer. Dr. Cullen places this genus of disease in the class locales and order tumores. He defines it a painful' scirrhous tumour, terminating in a fatal ulcer.

Any part of the body may be the seat of this disorder, though a gland is generally, if not constantly, its immediate situation. The obstruction is in the minuter vessels, and the adjacent parts are affected in consequence.

"It is probable,"according to Mr. Pearson, "that any gland in the living body may be the seat of a cancerous disease; but it appears more frequently as an idiopathic affection in those glands that form the several secretions, than in the absorbent glands; and of the secreting organs, those that separate the fluids, which arc to be employed in the animal economy, suffer much oftener than the glands which secern the excre-mentitious part of the blood. Indeed it may be doubled whether an absorbent gland ever be the primary seat of a true scirrhus. Daily experience evinces that these glands may suffer contamination from their connection with a cancerous part; but, under such circumstances, this morbid alteration being the effect of a disease in that neighbourhood, it ought to be regarded as a secondary and consequent affection. I never yet met with an unequivocal proof of a primary scirrhus in an absorbent gland; and if a larger experience shall confirm this observation, and establish it as a general rule, it will afford a material assistance in forming the diagnosis of this disease. The general term scirrhus has been applied, with too little discrimination, to indurated tumours of the lymphatic glands. When these appendages of the absorbent system enlarge in the early part of life, the disease is commonly treated as strumous; but as a similar alteration of these parts may, and often does, occur at a more advanced period, there ought to be some very good reason for ascribing malignity to one rather than the other. In old people the tumour is indeed often larger) more indurated, and less tractable, than in children; but when the alteration originated in the lymphatic glands, it will very rarely be found to possess any thing cancerous in its nature."however, in men, a cancer most frequently seizes the tongue, mouth, or penis; in women, the breasts or the uterus, particularly about the cessation of their periodical discharges; and in children, the eyes. Sometimes at the breast there is a hard and unequal tumour, attended with pain, which is not quite constant, and a burning heat much like what happens in cancer, whence it is called zaruthan, a spurious cancel'.