Page:The American Cyclopædia (1879) Volume IX.djvu/487

 ITAED ITCH 469 1TARD, Jean Marie Caspard, a French surgeon, born at Oraison. Provence, in 1775, died in Paris, July 5, 1838. At 18 he was appointed by the revolutionary committee surgeon of the military hospital of Toulon, although he had never read a medical book or seen a surgical operation. He devoted himself to study, and two years later was made a surgeon of the second class at the hospital of Val de Gr&ce. In 1799 he was appointed physician of the institution for deaf mutes, where he became known by his efforts to instruct a young man found wild in the forests of Aveyron. (See IDIOCY.) In 1801 Itard published a memoir giving the results of a year's effort in instruct- ing him, and in 1807 another giving the final re- sults, lie next gave his attention to the train- ing of deaf mutes in articulation, in which he succeeded almost as well as Pereira. In 1821 he published an elaborate work, in 2 vols. 8vo, on the diseases of the ear and of the sense of hearing. He also wrote a treatise on pneu- mothorax. ITASC I, a N. county of Minnesota, bounded N. by Rainy lake and Rainy Lake river, sepa- rating it from British America, and drained by several tributaries of that stream, and by the Mississippi ; area, about 9,600 sq. m. ; pop. in 1870, 96. Its surface is uneven and diversified by many small lakes. ITASCA, Lake of, a small body of water in Minnesota, on the N. W. border of Oass co., being one of the uppermost of the multitude of lakes which form the sources of the Missis- sippi river. It lies in lat. 47 10' N., Ion. 95 W., near the summit of the Hauteurs de Terre, the watershed between the Red river of the North and the streams flowing to the gulf of Mexico, 1,575 ft. above the level of the sea. It is a beautiful sheet of water, surrounded by hills, and its shores are clad with pines. It was discovered by Schoolcraft, July 13, 1832. The remotest source of the Mississippi is a small rivulet rising among the hills a few miles S. of this lake, and falling into it after forming a number of little basins. The stream issues from the N. end of the lake 10 or 12 ft. wide, and 12 or 18 in. deep. ITAWAJIBA, a N. E. county of Mississippi, bordering on Alabama, and drained by Toin- bigbee river ; area, about 600 sq. m. ; pop. in 1870, 7,812, of whom 986 were colored. It has a level or undulating surface, almost with- ouWimber. The soil is a dark, rich loam, con- taining much lime. The chief productions in 1870 were 7,053 bushels of wheat, 122,363 of Indian corn, 24,942 of sweet potatoes, and 1,865 bales of cotton. There were 1,420 horses, 2,235 milch cows, 3,915 other cattle, 6,130 sheep, and 9,734 swine. Capital, Fulton. ITCH, or Stables, a parasitic disease of the skin. There is no doubt that the true charac- ter of scabies was known among the ancient Greeks and Romans, but the animal was sup- posed to be a louse. Avenzoar in the 12th cen- tury alluded to its parasitic nature ; and Aldro- vandus about 1600 gives a good description of the animal, but says it has no legs. Mouf et at the same time says it is identical with the mite inhabiting cheese. Occasionally after this we find mention of this parasite in the writings of the great medical fathers, but it was generally forgotten when the grand scientific hoax was played in 1812 by the medical student Gales in Paris, who was cunning enough to substitute a cheese acarus concealed beneath his nail, and thus deceived the judges on the prize offered to the discoverer of the cause of this disease. The Corsican Renucci finally established its reality, taught by the old women of his birthplace, and Raspail gave the first scientific description of the animal in 1839. Since then the best ob- servers of its habits have been Bourguignon, Eichstedt, Schinzinger, and Hebra. The sar- coptes hominii, or acarus scabiei, presents three forms. The mature female is discernible by the unaided eye, as a white speck ^ of an inch long by yV of an inch broad. It is white, and resembles in shape a tortoise shell, with an arched back and flat belly. On the back are seen bristles or hairs, and little spines. The skin is tough, and shows irregular trans- verse parallel rings. There are four pairs of legs, two of which are situated in front and project beyond the anterior, the oth- ers toward the pos- terior end of the body. The two anterior pairs of feet are provided with sucking disks, and with hairs or bris- tles armed at their ex- tremities with minute claws ; the two poste- rior pairs of feet have no sucking disks, but only long bristles and small claws. The head is bluntly conical, somewhat retractile, and situa- ted between the anterior feet. The mouth con- sists of a double upper and under lip, between which play the jaws armed with teeth, moving in a horizontal direction up and down, like the blades of scissors over each other, and resem- bling the claws of a lobster. Eyes are want- ing. The male is only half the size of the fe- male, of a blackish color and flattened form. It has sucking disks instead of bristles upon the fourth pair of feet. In other respects it resem- bles the female. The young, when first hatch- ed, have but three pairs of legs, and in them no distinction of sex is noticeable. In order to become mature they undergo three separate stages of torpidity, before each of which the body is fat and large in comparison with the extremities. During these they burrow into the skin. By the first process they acquire the wanting pair of legs. When mature the female digs a shallow burrow, and after impregnation ceases to creep over the outer skin, but pene- Acarus scabiel, magnified.