MITLA. 633 MITOSIS. tance away, on an isolated hill, are the remains of a fort. The building.^, which are worthy of the name of temples or |)alaees, are ma.ssive, reetan^nilar structures of dressed stone, set on i)yramidal |jlatforms, and erected with surprising accuracy. The stones, usually of large size, and weighing as high as fifteen toirs, are laid with such pre- cision that the joints are scarcely discernible and for this reason little mortar was required. The ground plan is simple and the buildings are, as a rule, long and narrow, each containing only a single room, while the walls are but one story in height. The grouping of the buildings is in the form of quadrangles. The walls, in many cases over four feet in thickness, are faced with dressed stone or plaster. Mosaic stonework like that of Palenque (q.v.) is used lavishly, the designs being frets derived from animal motives. The exterior walls have no openings, but the doorways, either single or triple, on the courts are imposing in their mas- sive treatment. There were no doors, but sockets for the insertion of awnings. Supports were worked out in the jambs. The rooms were ceiled with beams of wood or slabs of .stone. In ease the room was wide, two sets of beams were used, su])ported on a row of large stone columns, some of which are 16 feet high and 80 inches in diam- eter. The roofs were massive and flat, and con- structed of beams, cross poles, and tilling material of brush, capped with rammed clay, similar to the metliod emijloyed by the Pueldo Indians of the Southwestern United States. The floors were made of a durable cement. On the whole, the Mitla buildings, wliile formal in plan and pro- file, show perfect and charming mosaic surface decoration, arranged in panels which exhibit great fertility of geometric design, as well as skill in execution. This feature, so far as known, is confined to two groups, though it was probably used in others. In the Arroyo group mural paintings resembling the pictographs of the co- dices were employed on the lintels. A note- wortliy feature is that sculpture is almost lack- ing in these buildings. Only one of the palaces has a basement story, and this cellar is cruciform. Several of these cruciform structures have been discovered in and near Mitla. but nowhere else in Mexico have they been observed, except at Chila in Puebla. It is .surmised that they were sepulchres of important personages. The character of the Mitla masonry is also seen in the interesting fortified hill situ- ated about one mile west of the village. In loca- tion, massiveness of construction, and skill in plan, it ranks with the ancient fortifications of Peru. Piles of rounded stones on the walls in- dicate that the fort was defended by slingers. The quarries from which the ancient ilitlans se- cured their materials have been discovered. The blocks were obtained by channeling with stone picks and hammers the full length of the stones and across the ends: then channels were cut down the sides and under the blocks until they could be broken off. Enormous stones in all stages of the work still remain in the quarry. Pottery of excellent design and finish has been found. Large, well-executed figurine vases are numerous. The color is dark-gray like the an- cient Zapotecan ware, but painted pottery is un- common here. Fan-shaped implements and a few celts of copper represent the onlj' metal objecta found. Consult: Charnay, Cit<!s vt ruiiics amvricaines (Paris, 18U3) ; Bandelier, Archwological Tour in Mexico in ISSl (Boston, 1884) ; Scler, Wand- niiilrrrirn von Mitla (Berlin, 1S!)5) ; Holmes, "Archaeological Studies Among the Ancient Cities of Mexico," in Fublications of the Field Colum- bian Museum (Chicago, 18U7); and .Saville, "Cruciform Structures Near Jlitla," in Bulletin of American Muxcuin of Xatural History, vol. xiii. (New York, 1000). MITO, me'td, or MYTHO. A town of Cochin- China. situated on an arm of the Mekong, about 4.5 miles southwest of Saigon, with which it is connected by rail (ilap: French Indo-China, E 5). It has a college and a hospital and is on the trade route between Cambodia and Annam. Popu- lation, about 27,000. MITO'SIS (Neo-Lat., from Gk. filmc, mitos, thread). The phenomena accompanying the di- vision of the nucleus of cells, a term proposed by Fleming in 1882 and superseding 'karyokinesis.' In cell-division the seat of the changes is the nucleus, in which portion of the cell the processes of cell-division originate. After the nucleus sub- divides the entire cell divides into halves, form- ing two new cells. Mitosis occurs not onl3' in the division of cells during growth, but the nucleus sulidivides, forming the first steps in reproduction or fertilization of all organisms. When the nucleus is about to divide, the chro- matic granules forming part of the nuclear sub- stance, and previously scattered throughout the central mass of the nucleus, become arranged in a row, forming a long thread, which extends STAGES IN HUTOSIS. 1, Preparatory to division : 2, early stape in separation of cliromosomes; 3, lat«r stacre in fteimration ; 4, form- ation of daugliter nuclei at poles, and of wall at equator of spindle. through the nucleus in an irregular spiral (s])irenie) and then divides into portions ("chromosomes') of fairly equal length. The chromosomes are shaped like long loops, which afterwards become shortened, thus giving rise to short loops, straight rods, or roinided granules. As a rule the number of chromosomes is constant for each species of plant or animal, and also for
