MOTION                                                    1271                                                           MOTT

The vines should be examined daily, and the larvę picked off and destroyed. In combatting the grape-leaf folder the same means should be employed. The white-marked tussock moth works much ruin on shade and fruit trees, stripping them of foliage. There are two broods a year. The cocoons are made in the trees, and on the cocoons the eggs are laid in a white, frothy mass. These eggs are conspicuous, and should be gathered and destroyed. See Army-Worm, Butterfly, Carpet-Beetle, Caterpillar and Codling-Moth. Consult Hodge: Nature-Study and Life; Holland: The Moth Book; and Treat: Injurious Insects.

Mo'tion, Laws of, generally the three great generalizations in which Newton described the effect of forces upon bodies. See Dynamics where these laws are stated. Compare, also, Newton's Laws of Motion by P. G. Tait for an extraordinarily clear, brief and elegant discussion of this subject.

Mot'ley, John Lothrop, an American historical writer, was born at Dorchester (now part of Boston), Mass., April 15, 1814. As a boy he had Bancroft for a teacher. His higher education he obtained at Harvard and in German universities, where he made a friend of Bismarck. His first great Vork, The History of the Dutch Republic (1856), was the result of nearly ten years' labor, much of the time being spent in Berlin, Dresden and The Hague in searching for materials. It was translated into Dutch, French, German and Russian, and established his fame. His room is shown to visitors in the queen's palace at The Hague, where he worked by royal invitation. The History of the United Netherlands followed in i860 and 1868. His last work was the Life and Death of John of Barneveldt, which is still another contribution to the history of Holland. His plan embraced a History of the Thirty Years' War, which was not finished. He also was a contributor to the Atlantic Monthly, and his letters to the London Times during the Civil War were effective in giving to the English people an understanding of the real question involved. He was United States minister to Austria from 1861 to 1867 and in 1869-70 minister to England. He died at the home of his daughter, who had married Sir Wm. Vernon Harcourt, in Dorsetshire, England, May 29, 1877. See Memoir by Oliver Wendell Holmes and Letters, edited by George William Curtis.

Mo'tor is any mechanical device by means of which energy is converted into motion. A windmill, used for driving a wheel or working a pump, is sometimes called an aėromotor. A machine by which the pressure of water in city mains is made to operate mechanical devices is usually Called a water-motor Motors for the use of compressed air have of late years been

much used, especially for the propulsion of street-cars. But the name is now most frequently applied to devices for the conversion of static into dynamic electricity. Motors operated by electricity have been devised to propel everything from a bicycle to a locomotive. Electric power is sometimes conveyed to the motor from a waterfall and sometimes from a storage battery. In any simple electric motor one finds a field-magnet, consisting of various coils of insulated wire on soft iron cores. These are connected by a yoke; and lines of force are developed around the pole pieces when a current of electricity is run through the coils. Within these lines of force rotates the armature. Of late, through improved devices, power is conveyed long distances; as from Niagara Falls (g. v.) to Buffalo; and power is conveyed to thousands of motors which operate innumerable mechanisms at a distance from the source. The discovery that natural forces can be made to store electric forces, which may in turn be reconverted into dynamic electricity at the other end of the wire by means of an electric motor, is one of the greatest discoveries of the 19th century.

Mo'tor Or'gan ( in plants ), a term applied to a portion of the leafstalk (petiole) which is sensitive to certain stimuli (see Irritability) and has a special structure enabling it to curve easily. Motor organs are most perfect in the bean and oxalis families, but exist also in some spurges {Euphorbia), the common mallow (Malva rotundifolia) and the velvet leaf (Abutilon Avicennos). To the eye the motor organ usually is of a different color from the rest of the leafstalk, and either larger or smaller. If the leafstalk is long, the motor organ will be at the base; if short, the whole stalk may be a motor organ. In compound leaves there may be motor organs at main and secondary (and even at tertiary) petioles. In contrast with the rest of the petiole the woody parts of the motor organs are gathered near the center, and the whole of the surrounding tissue is made of thin-walled cells. When their turgor (which see) increases on one side and decreases on the other, the motor organ becomes curved, carrying the leaves into a new position. See Movements.

Mott, Mrs. Lucretia Coffin, an American Quaker, was born at Nantucket, Mass., Jan. 3, 1793. She became a preacher and traveled through New England, Pennsylvania, Maryland and Virginia, preaching the Quaker doctrines and opposing intemperance and slavery. She was active in organizing the antislavery society at Philadelphia in 1833, and proceeded as a delegate to the world's antislavery convention at London in 1840. She was also prominent in woman's rights assemblies. She died on Nov. 11, 1880