lidæ. This class of alternation of generations has been called metagenesis. As an example of it, one of the Hydrozoa may be taken. The free-swimming jellyfishes are diœcious, and produce the male and female gametes, which unite in the water. The larvæ which result from the development of the eggs settle down, become attached and develop into a hydroid, which produces a colony by budding. Certain buds are set free as jellyfishes, and these in turn set free the gametes. Thus the hydroid form (A) and the jelly form (B) alternate with each other.
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Alternate Generations in Hydroids.
A Campanularian Hydroid: a, root-stock (hydrorhiza); b, b, hydranths; c, c, gonangia, containing medusa buds; d, a free- swimming, gameter-producing medusa; e, ciliated larva before settling down.
In certain respects the gamete-producing generation of spermatophytes among plants (see above) resembles the maturation period preceding the formation of gametes in the higher animals; and it has been suggested that even in vertebrates, including man, we have an alternation of generations: (1) the non-sexual generation beginning with fertilization and ending with the primary oöcyte or primary spermatocyte; (2) the sexual generation beginning with the primary germ-cell and ending with the ripe germ-cell (two-cell division).
Bibliography. J. J. S. Steenstrup, On the Alternation of Generations, translated by Busk (London, 1845); J. V. Carus, Zur nähern Kenntniss des Generationswechsels (Leipzig. 1849); R. Leuckart, Ueber den Polymorphismus der Individuen, etc.; ein Beitrag zur Lehre vom Generationswechsel (Giessen, 1851).
AL'TERNA'TOR. See Dynamo-Electric Machinery.
ALTGELD, alt'geld.
John Peter (1847-1902). An American politician. He was born in Germany, and was brought to the United States when an infant. His parents settled near Mansfield, O. He entered the Union army at the age of sixteen, and fought until the close of the war. After teaching school for some time in Missouri, he began the study of law, and was admitted to the bar in 1869, his election as State Attorney of Andrew County, Mo., following in 1874. He was judge of the superior court of Chicago from 1886 to 1891 and Governor of Illinois from 1893 to 1897, in which capacity his pardon of the anarchists Fielden, Neebe. and Schwab excited wide comment. As a prominent advocate of free silver, he was an active supporter of William J. Bryan during the Presidential campaigns of 1896 and 1900. He did much to advance the cause of prison reform, and was a vigorous and effective public speaker.
ALTHÆ'A (Gk. i/.iSom, althaia, wild or
marsh mallow). A genus of plants of the order
Malvaceæ, differing from the true mallow, Malva,
chiefly in its six to nine-cleft calyx. The species,
natives of Europe and Asia, and naturalized in
North America, are annual and perennial shrub-
by plants that are much grown for their showy
flowers. The more common species are the marsh-mallow, Althœa officinalis, and the hollyhock. Althœa rosea. The name Althaea is applied also by gardeners to the Rose of Sharon, Hibiscus syriacus. See Hollyhock; Marsh-Mallow; Hibiscus.
ALTH.ÆA, or ALTHEA (Gk.' AA^aiu. Althaia ) . In Greek story, the mother of Jleleager (q.v.), whose life the Fates had told her should last as long as a log of wood burning upon the hearth at his birth should be unconsumed. She quenched and long preserved it, bvit finally in
anger at him set it on fire and so ended his life.
She was the daughter of Thestius, wife of CEneus,
King of Calydon, and mother also of Tydeus
and Dei'anira.
ALTHE'A. In Richard Lovelace's To Althea
from I'risoii, and Other Lijrics. a poetical name
apjilied to his love Lucasta, who is understood
to have been Lucy Sacheverell.
ALT'HORN. See Saxhorn.
ALTHORP, Lord. See Spencer, John Charles.
ALTHU'SIUS, Johannes (1557-1638) . Pro- fessor of law and ethics at Herborn. He pub- lished the first treatise on politics •nTitten in Germany. He made the basis of social life an express or implied contract between associated men. thus anticipating Rousseau's famous social contract theory. He defended resistance to usurpation of the rights of the people, from whom all rights proceed. He put combinations of workmen in the category of monopolies to be ro.gulated. His chief works are: Polilica Mctho- dice Digesta (Herborn. 1G03) ; Jnrispriidentia Fomana (Herborn, 1588) : Dicoroloriicw Lihri Trcs Totum ct Uitii^erstim Ju>!, quo Utimiir, Meth- odicc Complectantcs (Herborn, 1017).
ALTIM'ETRY (Lat. altiis. high -f Gk. fitrpov, mctron, measure). The art of ascertaining altitudes geometrically or measuring vertical angles by means of a quadrant, sextant (q.v.), or theodolite (q.v.). 'hen used for this purpose, the instrument is known as an altimeter.
ALTIN, al-tin'. Altyn-Nor (Tartar altun, golden + nor, lake), or Telets Lake. A freshwater lake in the government of Tomsk, Siberia (Map: Asia. H 3). It is in the Altai Mountains, 1600 feet above the sea level, and has an
