consult Gadow, Amphibia and Reptiles' (London 1901); Boulenger, Catalogue of Patrachia in British Museum (London 1882); and many papers in English scientific periodicals: Cope, Batrachia of North America' (Bulletin 34, United States National Museum, Washington 1889), which contains an extensive bibliography; also Amphibia,' by Lyddeker, Cunningham, Boulenger and Thompson (London 1912). Dickerson's 'The Frog Book' (New York 1916) gives a popular account of the group.

PLANTS.

Certain

The

AMPHIBIOUS plants, such as some liverworts, the knot-weed, Polyganum amphibium, Sagittaria heterophylla, the water-buttercup, Ranunculus aquatilis, and the mermaid-weed, Proserpinacea. pallustris, can grow and flourish either in water or in air, and are consequently called amphibious. same plant will often assume great difference of form in the two environments. This is especially shown in the leaves. Those of Polygonum amphibium, hairy in air, are smooth in the water. Sagittaria has ordinary leaves in the air, but phyllodes in the water. Ranunculus and Proserpinacea have dissected leaves in the water, but leaves of the familiar broad-bladed form on land, with transitional forms at the surface of the water. It has been shown that the stimulus which produces this change in leaf-form is the transpiration which the leaf undergoes in air. Stems growing under water become flaccid at the surface, and the same plant which in the air has strength enough to hold itself erect will depend in the water on the surrounding medium for its support. Consult Coulter, J. M., Barnes, C. R., and Cowles, H. C., A Text-Book of Botany) (Vol. II, New York 1911).

AMPHIBOLE, am'fi-bōl (from the Greek amphibolos, "doubtful," in allusion to the difficulty of distinguishing it from pyroxene). In mineralogy, (1) a common mineral, crystallizing in the monoclinic system, and varying greatly in chemical composition. The name was first given by Hauy in 1801 as distinguishing a species of which he regarded hornblende and actinolite as varieties. In 1809 he included tremolite also. In general, the species may be described as a normal metasilicate of calcium and magnesium, associated with iron, manganese, sodium, potassium and hydrogen.

(2) Amphibole Group.- An important group of minerals, including the species described above, and taking its name therefrom. Its constituent species are widely different in chemical composition, and are closely allied to the members of the pyroxene group. All the species of the amphibole group have a prismatic cleavage of from 54° to 56°, and they also exhibit close relationships in the optical properties. All the species of the pyroxene group have a fundamental prism with an angle of 93° and 87°, the corresponding angle in amphibole being 56° and 124°. The specific gravity of the pyroxenes is usually higher than that of the species of the amphiboles with which they are likely to be confused. Alkalis are met with more commonly in the amphiboles, and magnesium is also more prominent in that group. The amphibole group is divided into three main

587

or

AMPHIBOLOGY, an equivocal phrase or sentence, not from the double sense of any of the words, but from its admitting a double construction, as "The duke yet lives that Henry shall depose." The word that may be ambiguous, and consequently the sentence may be an example of equivocation, not amphibology. Fallacies of amphibology are purely verbal, and seldom found apart from other types of verbal fallacy. They are so obvious that they do not constitute a serious source of unsound thinking. AMPHICTYONIC LEAGUE COUNCIL, in ancient Greece, an assembly composed of deputies from 12 Greek tribes, each of which sent two deputies, who assembled each year at Delphi, and again at Thermopylæ, with great solemnity; composed the public dissensions, and the quarrels of individual cities, by force or persuasion; punished civil and criminal offenses, and particularly transgressions of the law of nations and violations of the temple of Delphi. It forbade the destruction of a city of the league or the obstruction of its water-supply in war or peace. After the decision was published a fine was inflicted on the guilty state, which, if not paid in due time, was doubled. If the state did not then submit, the whole confederacy took arms to reduce it to obedience. The assembly had also the right of excluding it from the confederation. An instance of the exercise of this right gave rise to the Phocian War, which continued 10 years (B. C. 355-346). The council also administered the Pythian games. Consult Tittmann, Über den Bund der Amphyctyonen' (Leipzig 1880); Freeman, 'History of Federal Government' (2d ed., London 1893).

AMPHICYON, a genus of extinct mammals, found fossil in Miocene rocks, which is usually placed among the extinct Canida (dogs), but has many bear-like features, such as plantigrade, five-toed feet and the structure of the ulna and radius. The largest species was about the size of a bear, but with a very dog-like head. It belonged to the Old World, but a closely allied American Miocene form is Daphanus.

AMPHINEURA. See MOLLUSKS.

AMPHION, in Greek mythology, son of Zeus and Antiope, his twin brother being Zethus. He is represented as being the oldest of

the Grecian musicians. In Lydia, where he married Niobe, the daughter of King Tantalus, he learned music and brought it thence into Greece. He reigned in Thebes, which he partly built, and it is said that at the sound of his lyre the stones voluntarily formed themselves into walls; also that wild beasts, and even trees, rocks and streams followed the musician. With the aid of his brother Zethus he is said to have avenged Antiope, who had been imprisoned and ill-used by his father, and to have bound Dirce, his stepmother, to the horns of a wild bull. This incident is supposed to be represented by the famous piece of sculpture, the Farnese bull, in the Farnese Palace at Rome.

a

It is

AMPHIOXUS, the lancelet, small animal of the marine sub-phylum Cephalochordata, of the great phylum Chordata (q.v.), to which the vertebrates belong. Its scientific name is Branchiostoma. From its somewhat worm-like form it was for a long time regarded as a worm by some authors and originally as a mollusk (Limax) by Pallas. now named Branchiostoma lanceolatum; lives buried in the sand just below low-water mark, the head or "oral hood" projecting above into the water. It also swims in a vertical or upright position, also frequently lying on side on the sand; and burrows head foremost rapidly downward in the sand. It extends along our coast from the mouth of Chesapeake Bay to Florida; also on the eastern coast of South America and in the north European seas, the Mediterranean, the East Indies and Australasia, the species being truly cosmopolitan. Another very closely allied genus, Asymmetron, includes two species, one of which occurs at the Bahamas and the other in the Louisade Archipelago, southeast of New Guinea.

one

The body of Amphioxus is about two inches in length, slender, compressed, pointed at each end, hence the generic name (Amphioxus, appi both, oğùs, sharp), the head-end being thin and compressed. The 62 v-shaped muscular segments are distinct to the naked eye. and alternate on the two sides. From the mouth to the vent is a deep ventral furrow and a slight dorsal fin extends along the back and beneath as far front as the vent, forming the ventral fin, while the wider portion at the tail is the caudal fin. The oral hood has a large median external opening, which is oral, surrounded with a circle of ciliated tentacles supported by semi-cartilaginous processes arising from a circumoral ring. At the bottom of this opening is the small mouth which leads directly into a large broad pharynx or "branchial sac," protected at the entrance by a number of minute ciliated lobes. The walls of this sac are perforated by long ciliated slits, of which there are more than a hundred pairs, comparable with those of the branchial sacs of ascidians and of Balanoglossus. The water which enters the mouth passes out through these slits, where it oxygenates the blood and enters the peribranchial cavity, thence passing out of the body through the abdominal pore (atriopore). The pharynx leads to the stomach with which is connected the liver or cœcum. There is a system of blood-vessels, but no heart. A contractile median vessel, the ventral aorta, beginning at the free end of

the liver and extending along the underside of the pharynx, sends branches to the sac and two anterior branches to the dorsal aorta. On the dorsal side of the pharynx the blood is collected by the two anterior trunks from the branchial veins which carry away the aërated blood from the branchial bars, and poured into a great longitudinal trunk or median dorsal aorta, by which it is distributed throughout the body. There are also vessels distributed to the liver, and returning vessels, representing the portal and hepatic veins. The blood-corpuscles are white and nucleated.

The vertebral column of the true vertebrates is represented in the lancelet by a notochord, a long, flexible, cylindrical rod pointed at both ends, which extends to the end of the The head far in front of the nervous cord. nervous cord is a rod-like structure which lies over the notochord. It is not divided into a true brain and spinal cord, though the cord is slightly enlarged at the anterior end, where a The rudimentary ventricle is said to exist. nerve-cord sends off a few nerves to the periphery, with a nerve to the single minute median eye. An olfactory pit opens externally on the left side of the snout and communicates with the central canal of the nerve-cord. The principal excretory organs are about 90 pairs of peculiarly modified nephridia, situated above the pharynx and in relation with the main cœlomic cavities. These have no common duct but empty into the peribranchial cavity. The reproductive glands are square masses or pouches, of which there are about 26 pairs attached in a row on each of the walls of the body-cavity. The individuals may be male or female, the only sexual differences being in the reproductive glands.

The

The eggs may pass out of the mouth or through the pore. Kowalevsky found them issuing in May from the mouth of the female and fertilized by spermatic particles likewise issuing from the mouth of the male. eggs are very small, 0.105 millimetres in diameter. The eggs undergo total segmentation, leaving a segmenta on cavity. The body-cavity is next formed by invagination. The blastoderm now invaginates and the embryo swims about as a ciliated gastrula. The body is oval and the germ does not differ much in appearance from a worm, starfish or ascidian in the same stage of growth. No vertebrate features are developed. Soon the lively, ciliated gastrula elongates, the alimentary tube arises from the primitive gastrula cavity, while the edges of the flattened side of the body grow up as ridges, which afterward, as in all vertebrate embryos, grow over and enclose the central nervous system. When the germ is 24 hours old it assumes the form of a ciliated flattened cylinder and now resembles an ascidian embryo, there being a nerve cavity with an external opening which afterward closes. The notochord appears at this time. In the next stage observed the adult characters have appeared, the mouth is formed, the first pair of gillopenings are seen, 11 additional pairs appearing. It thus appears that while the lancelet at one time in its life presents ascidian features, yet, as Balfour states, "all the modes of development found in the higher vertebrates are to be looked upon as modifications of that of

Amphioxus. Consult Willey, A., Amphioxus and the Ancestry of the Vertebrates' (New York 1894). Any work on the Chordates or Vertebrates will contain some material on Amphioxus.

AMPHIPODA, an order of Crustacea, in which the body is compressed and usually arched. There is no carapace or distinct cephalothorax, but a small head, bearing two pairs of antennæ, a pair of jaws (mandibles), and three pairs of maxillæ. The thoracic segments are separate and like those of the abdomen, not being fused and united with the head segments. Respiration is performed by lamellate or leaflike gills arising from the thoracic feet. The three anterior abdominal segements bear swimming feet, while the three posterior bear posteriorly directed feet adapted for springing. The heart lies forward, and the eyes are simple. The amphipods are represented by the common beach-flea or beach- or sand-hopper (Orchestia agilis); by Gammarus, or "scud," species of which live both in the sea and in fresh-water. Extreme forms are the ghost-like or skeleton-like attenuated Caprella, abounding in eel-grass below low tide; and which in walking loop the body somewhat like a geometricid caterpillar. Another form is Chelura terebrans, which burrows in wood, in company with the gribble. It is very active and frequently destructive to submerged piles. Other forms are eyeless and live in caves or dark wells.

AMPHIPOLIS, an important city of Thrace or Macedonia; at the mouth of the Strymon River, 31 miles from the Egean. It was founded as an Athenian colony about 436 B.C.; was captured by Sparta in 424 B.C.; and near it the Spartans defeated the Athenians in 422 B.C. in a battle in which Cleon, the Athenian general, and Brasida, the Spartan conqueror of Amphipolis, were both killed. Subsequently it became a Macedonian possession; was called Popolia in the Middle Ages; and its site is now occupied by the Turkish town of Yenikeui.

AMPHISBÆNA, one of the degraded worm-shaped lizards of the family Amphisbanida, which lead an entirely subterranean life, burrowing like earth-worms. They have a soft skin forming numerous rings and containing only vestiges of scales except upon the head. External limbs are absent (except in one genus), and only vestiges remain of any limb-bones. Their tails are so short and blunt that they are popularly said in some countries to have two heads, whence the scientific name of the group. There is also a legend that when cut in two, the two ends will find one another and reunite. This notion is strengthened by their ability to move either forward or backward with equal ease. About a dozen genera and more than 60 species are known, most of which inhabit the warmer parts of America and Africa; some also live in Asia Minor and in Spain. They are frequently found in ants' nests, and have been called "mothers of ants" in consequence. Their eyes and ears are concealed beneath the skin. A common species in South America and the West Indies (Amphisbana fuliginosa) is checkered black and white, and is from one to two feet in length. Like the others it feeds upon worms and small

insects found under the surface of the ground. They are quite harmless.

AMPHITEATROV, Alexander Valentinovitch, vä-len-te-no'vich äm-fe-ta-a'trof, a popular Russian writer of the naturalistic school. He was born at Kaluga (central Russia) of ecclesiastical parentage in 1862, and studied music and jurisprudence, the latter at the Moscow University. His literary career began in 1887, when his light verse and prose commenced to appear in various humorous periodicals. As special correspondent of the foremost Russian daily, Novoye Vremia, he at one time attracted considerable attention under the pseudonym of "The Old Gentleman." In 1902 he was exiled to Siberia for certain advanced views expressed in his own periodical, Russia. Since 1905 he has been living abroad, where he edited a progressive periodical called The Red Banner. Among his extra-literary achievements perhaps the most important was the founding at Paris of The Russian School of Social Science, at which he delivered courses of lectures.

are

Amphiteatrov .has been an extremely prolific writer, whose literary output, if collected, might easily fill half-a-hundred volumes. His works already published include numerous novels, dramas, critical and biographical essays, studies in history and an endless variety of humor. As none of these are available in English, it would be superfluous to enumerate them in a general reference work intended for English readers. A few characteristic titles of his more important novels The Blood of Alimov (1884), a decidedly zolaesque work with which the author first attracted general attention; 'Fiedka the Murderer) (1892), a study in hereditary predisposition; Victoria Pavlovna (1907), a most interesting work dealing favorably with the woman question; 'The Dusk of the Demigods' (1908), a twovolume work depicting the vanities and tribulations of actors, playwrights and singers, and "The Men of the Eighties and Nineties' (190710), also in two volumes, constituting the initial works of a projected series which was intended to picture, in leisurely Balzac fashion, Russian society from 1880-1910. His non-fiction includes A Literary Album,' a volume entitled Humor,' and a very creditable study of antisemitism. His dramas are commonly adaptations from his novels - and sometimes the

author reverses this process of literary

manufacture.

Amphiteatrov is not in any sense a great Russian writer - not even when judged by contemporary Russian standards. He lacks the originality of Gorky, the inventiveness of Andreyev and the art of Artsybashev (qq.v.). Although he, too, is a realist, his realism is rather of the simple physiological kind of Zola than of the great Russian variety developed by Gogol, Tolstoy and Dostoyevsky (qq.v.). His special interests in human nature lie with the play of temperaments and hereditary predispositions, both well illustrated in The Dusk of the Demigods,' teeming with alcoholics, and in 'The Men of the Eighties,' full of degeneracy. This interest in the abnormal and subnormal human types, which is suggestive of Dostoyevsky and which links Amphiteatrov somewhat with Andreyev, makes most of his