IRRITABILITY 200 IRVING N. Dak., Okla., Ore., S. Dak., Utah, Wash., Wyo. , Texas. The funds for this work come mainly from the sale of public lands and from oil-leasing royalties. According to the Reclamation Extension Act of Aug. 13, 1914, the money expended is returned to the fund by the settlers, through pay- ments in fifteen or twenty annual install- ments, without interest. Over 400,000 persons are living on the 1,780,000 acres irrigated by the Reclamation Service. The value of the crops in 1920 on the project land was nearly $114,000,000. In 1902 the average value of the desert land was not more than $10 per acre. Since the government has undertaken the irri- gation of this territory, the average value has increased to $200 per acre, or a total of over $350,000,000. More than 13,000 miles of canals and ditches have been built on the projects. The Reclamation Service in 1920 served 2,845,000 acres of land, including 1,662,000 acres for which the government fui-nished the total water supply, and 1,183,000 acres to which the government sent stored water as an aid to the supply of private streams. The Mexican Government has taken an inter- est in the question of irrigation, and has appropriated over $20,000 to be used for the improvement of the Yaqui River Val- ley, Sonora. The table on page 199 shows the principal United States irrigation projects and their cost up to June 30, ,1919. IRRITABILITY, in anatomy, vital contractibility, the property of visibly contracting even after death, on the ap- plication of a stimulus. The right auricle has been found irritable for 16% hours after death. A voluntary muscle has been found irritable 24 hours after death. In botany, excitability of an extreme character, in which an organ exhibits movements different from those com- monly met with in plants. Its known causes are three — atmospheric pressure, spontaneous motion, and the contact of other bodies. Thus plants sleep, the com- pound leaves, where such exist, folding together; so also the sensitive plant shrinks from touch. IRRITANT, in pharmacy, that which produces irritation or excitement of any muscle, nerve, or other organ or part of the body. A pure irritant is a poison producing inflammation without corro- sive action on the tissues. IRTISH (er'tish) , a river of Siberia, the chief affluent of the Obi, rises at the E. end of the Altai Mountains, passes through Lake Saisan, breaks through the Altai in the W. at the bottom of a savage gorge, and flows N. W. across the steppes of Western Siberia to join the Obi, from the left, at Samarow. At that point it has a width of 2,000 yards; its total length is 1,620 miles; the area of its basin, 647,000 square miles. The im- portant towns of Semipalatinsk, Omsk, and Tobolsk stand on its banks. From April to November it is navigable from its mouth as far as Lake Saisan; during the rest of the year traffic is carried on by means of sledges. Its current is gradually shifting E. Its best known tributaries are the Buchtarma and Om from the right, and the Tobol and Ishim from the left. IRUS (i'rus), a beggar of Ithaca and lover of Penelope, killed by Ulysses by a blow with his fist. IRVING, SIR HENRY, an English actor; born in Keinton, England, Feb. 6, 1838. His family name was Brodribb, which was changed to Irving by royal patent. He was trained to mercantile life, but went upon the stage in 1856, appearing in London a few years later. His roles include Mephistopheles, Ham- let, Coriolanus, King Lear, Louis XI, Malvolio, Macbeth, and a repertory that has been presented not only in England, but in the United States, Australia, and France. He was knighted in 1895. He has published an edition of Shakespeare. He died Oct. 13, 1905. IRVING, HENRY BRODRIBB, an English actor, son of Sir Henry Irving, born in 1870 in London. He was edu- cated at New College, Oxford, and en- tered the bar in 1894. He soon gave this up for the stage, where he soon be- came a prominent figure. He became a manager in 1902. In 1906 and 1907 he made a tour in America which was fol- lowed by tours in Australia and South Africa. Following his return from the latter, he leased the Savoy Theater. He appeared as star in many successful plays. He wrote "Life of Judge Jef- freys" (1898); "Occasional Papers" (1906); "The Trial of Mrs. Maybrick" (1913). He died in 1919. IRVING, ISABEL, an American ac- tress, born in Bridgeport, Conn., in 1871. She made her first appearance on the stage in 1887, and within a short time had become the leading woman at the Lyceum Theater in New York and in John Drew's Company. For several years she played leading parts in Eng- land. She played as leading woman and as star in many important plays. In 1889 she married William H. Thompson. IRVING, LAWRENCE (SYDNEY BRODRIBB), an English actor and
