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* LOCOMOTOR ATAXIA. 393 LOCUS DELICTI. ease. The upper limbs are soinelimes aiFected, so that, though the hauds retaiu all their natural muscular power, the suU'erer caiinut unfasten a button, or pick up a pin, or feed himself. As the disease progresses, this muscular incoiirdina- tion (ataxia) increases uutil the person alfected is unable to walk at all. Paralysis of various muscles maj' occur, notably of some of those of the eye. The involvement of the bladder pro- duces a loss of the power of urination, and gen- eral weakness results in death. Although usual- ly going to a fatal termination, the disease is sometimes arrested, and appears to be quite conquered particularly in its' earlier stages. In most cases it extends over several years. Loco- motor ata.xia arises from disease of a portion of the posterior spinal ganglia, later involving the posterior columns and the posterior nerve-roots, which become atrophied and degenerated. Tlie e.xciting causes are not well understood, but ex- posure to cold, overexertion, privation, intem- perance, and mental anxiety have been suggested as probable. It is probable that syphilis is the most important single cause, at least 60 to 70 per cent, being due to this alone, or to sypliilis combined with alcoholism. Anti-syphilitic treat- ment results in amelioration in some cases. It is sometimes hereditary, and is more common among males than females. It is developed usually not till middle life, from the age of thirtj' to fifty. Beyond alleviation of pain, little can be done by medicine, though many I'emedies have been tried. Electricity has been recommended by eminent authorities. Perhaps the best course is to attend carefully to the general health and regimen. Much can be done for the ataxia by systematic exercises carried out imder a physician's in- structions. Consult Potts, yeri-ous and Mental Disriisr (Philadelphia and Xew York, 1900). LOCO-WEED. See Astkagalcs; Loco Dis- ease. LO'CRI, or LoCRi Epizephykii. See LocEis. LO'CRIS (Lat., from Gk. Aiitpis, LoAns). A district of ancient Greece. Legend told of a King Locros, a descendant of Deucalion, who ruled over the Leleges on the coast of the mainland opposite Eubcea, and whose wife, a daughter of the King of Elis, bore to Zeus a son Opus. Later, moved by the strife of his sons, Locros is said to have crossed the mountains to the southwest and formed a new settlement on the shores of the Corinthian Gulf. The Locrian tribes seem to have been forced asunder by the invasions from the north, and in historic times two distinct tribes were known. The eastern Locrians. di- vided into the Opuntian and Epicnemidian, dwelt opposite the island of Eubcea on the northeast coast of Greece. The western Locrians, called Ozolian, lived on the Corinthian Gulf, west of Phocis. Neither division played any prominent part in Greek history. Early in the seventh cen- tury B.C. a colony, probably of the Gpuntian Locrians, settled at Cape Zepliyrium in Magna Gra-cia, and a few years later moved to a site about five miles south of the modern Gerace, where they founded Locri Epizephyrii. The city never attained the prosperity of the great trading colonies, but seems to have been a pros- perous farming community. It was celebrated for its severe but just code of laws, attribut- ed to Zaleucus. who is said to have lived about the middle of the seventh century B.C., and to have been the first Greek to prepare a written code. So highly was his work esteemed that it is said to have remained unaltered for centuries. The Locrians won great fame by defeating the much more powerful city of C'rotona in a bloody battle at the Riv^r Sagras about B.C. 525, a vic- tory which they ascribed to the personal inter- vention of the Dioscuri. The town was seized by the younger Dionysius, after his expulsion from Syracuse in B.C. 356, and ruled with the greatest tyranny until his return to Syracuse in B.C. .346, when the inhabitants rose and took a frightful vengeance on his family, who had been left be- hind. During the wars of Rome with Pyrrhus and Carthage, the city was alternately occupied by the opposing parties, and its temple of Per- sephone was finally plundered by the Romans, who, however, made restitution later. Soon after it seems to have declined in importance, but is mentioned by Proeopius in the sixth century A.D., and was probably destroyed by the Sara- cens. In 1889 and 1890 excavations near Gerace brought to light the foundations of a temple, pos- sibly that of Persephone. Consult Riimische Miltheilungen. vol. v. (1890), and Aniike Denk- mdler, i. 5 (1890). LOCUS (Lat, place). The place of all points satisfying a given condition. For example, the circumference of a circle whose centre is O and whose radius is r is the locus of all points satis- fying the condition of being in the same plane and at a distance r from a fixed point O in that plane. In space, the locus is the surface of a spliere of centre O and radius r. In proving a theorem concerning the locus of points, it is necessary and sufficient to prove two things : that any point on the supposed locus satisfies the given condition, and that any point not on the supposed locus does not satisfy the condition. A few important propositions of loci are: (1) The locus of points equidistant from two given points is the perpendicular bisector of the line joining them; (2) the locus of points equidistant from two given lines consists of the bisectors of their included angles; (.3) the locus of points equidis- tant from three given points is the perpendicular to their plane passing through the centre of the circle on which they lie; (4) the locus of points the sum of whose distances from two fixed points is constant is an ellipse whose foci are the given points; (5) the locus of the vertices of constant angles subtended by a given line-segment is an arc of which that segment is the cord; (6) if a pair of variable quantities, x, ij, are connected by an equation, and each pair of values is repre- sented by a point in a plane, these points will be on a definite curve called the locus or gi'aph of the equation. (See Coordinate.s.) Thus the study of cur^'es by analytic methods is a develop- ment of the theory of loci. (See Curves.) The method of loci in pure geometry was ex-tensively used by the Greek geometers, particularly .pol- lonius, Hippias, Eudoxus, Niconiedes. and Di- odes. The methods of ApoUonius were restored by Robert Simson in his De Locis Planis (1748). but as an analytic instrument the theory of loci dates from Descartes (1037). LOCUS DELICTI (Lat., place of crime or wrong). In criminal law, the place where a crime is actually committed. The question of /ocu.9 delicti usually arises when a wrongfiil act is commenced in one jurisdiction and continued