Page:Encyclopædia Britannica, Ninth Edition, v. 3.djvu/62

Rh after a course of 250 miles, almost due N., for the most part through a low and swampy region, falls into the Gulf of Uraba or Darien. The gold and platinum mines of Choco were on some of its affluents, and its sands are still auriferous. The river has attracted considerable attention in connection with schemes for the construction of a ship- canal across the isthmus. It is navigable for small vessels for about 140 miles.

 ATREK or, a which rises in the mountains of, and flows W. along the borders of and the n possessions, till it falls in the south-eastern corner of the , a short distance to the N. of.

 ATREUS, in Greek Legend, a son of Pelops, had, with his brother Thyestes, settled in Mycenae, where he succeeded Eurystheus in the sovereignty, in which he was secured by the possession of a lamb or ram with a golden fleece. His wife Ae rope, a daughter of Minos, bribed by Thyestes, assisted the latter to carry off the ram. But Zeus, in the interest of Atreus, wrought a miracle, causing the sun which before had risen in the west to rise in the east. Thyestes was driven from Mycenae, but returned to his brother begging to be forgiven. Atreus, appearing to welcome him, invited him to a banquet to eat of his own son, whom he had slain. From this crime followed the ills which befel Agamemnon, the son of Atreus (.^Eschylus, Agam. 1583, foil.)

 ATRI or ATRIA, the ancient Hadria, a town of Naples, in the province of Abruzzo Ulteriore I., situated on a steep mountain 5 miles from the Adriatic, and 18 miles S.E. of Teramo. It is the see of a bishop, and has a cathedral, a parish church, and several convents and hospitals. It con tains 9877 inhabitants. Remains of the ancient city have been discovered to the S. of the present site, consisting of the ruins of a theatre and baths, with pavements, and vases of Greek manufacture. It was a very flourishing commercial port at an early period, but had declined into a small town in the time of Strabo. Its modern revival has been furthered by the excavation of new canals.

 ATRIUM, the principal apartment in a Roman house, was entered through the ostium or janua, which opened off the vestibulum, a clear space between the middle of the house and the street, formed by the projection of the two sides. It was generally quadrangular in shape, and was roofed all over, with the exception of a square opening, called compluvium, towards which the roofs sloped, and by which the rain-water was conducted down, to a basin (impluvium) fixed in the floor. The opening in the roof seems sometimes to have been called impluvium (Terence, Eun., iii. 5 ; Phorm., iv. 4). In the early periods of Roman civilisation, the atrium was the common public apart ment, and was used for the reception of visitors and clients, and for ordinary domestic purposes, as cooking and dining. In it were placed the ancestral pictures, the marriage-couch, the focus, or hearth, and generally a small altar. Here, too, were kept the looms at which the mistress of the house sat and span with her maid-servants. At a somewhat later period, and among the wealthy, separate apartments were built for kitchens and dining-rooms, and the atrium was kept as a general reception room for clients and visitors. It appears sometimes to have been called cavcedium, but the relation of these two is somewhat obscure. According to some authorities, the cavcedium was simply the open space formed when the impluvium was surrounded with pillars to support the roof ; according to others, the cavce dium was really the principal room, to which the atrium served as an antechamber. , in Ecclesiastical Antiquities, denotes an open place or court before a church. It consisted of a large area or square plat of ground, surrounded with a portico or cloister, situated between the porch or vestibule and the body of the church. In the centre was placed a fountain, wherein the worshippers washed their hands before enter ing church. In the atrium those who were not suffered to advance farther, and more particularly the first class of penitents, stood to solicit the prayers of the faithful as they went into the church. It was also used as a burying- ground, at first only for distinguished persons, but after wards for all believers.

 ATROPHY (a priv., [Greek]], nourishment), a term in medicine used to describe a state of wasting due to some interference with the function of healthy nutrition. In the living organism there are ever at work changes involv ing the waste of its component tissues, which render neces sary, in order to the preservation of life, the supply and proper assimilation of nutritive material. It is also essen tial for the maintenance of health that a due relation exist between these processes of waste and repair, so that the one may not be in excess of the other. When the appro priation of nutriment exceeds the waste, hypertrophy or increase in bulk of the tissues takes place. (See HYPER TROPHY.) When, on the other hand, the supply of nutritive matter is suspended or diminished, or when the power of assimilation is impaired, atrophy or wasting is the result. Thus the whole body becomes atrophied in many diseases ; and in old age every part of the frame, with the single exception of the heart, undergoes atrophic change. Atrophy may, however, affect single organs or parts of the body, irrespective of the general state of nutrition, and this may be brought about in a variety of ways. One of the most frequently observed of such instances is atrophy from disuse, or cessation of function. Thus, when a limb is deprived of the natural power of motion, either by paralysis or by painful joint disease, the condition of exercise essen tial to its nutrition being no longer fulfilled, atrophy of all its textures sooner or later takes place. The brain in imbeciles is frequently observed to be shrivelled, and in many cases of blindness there is atrophy of the optic nerve and optic tract. This form of atrophy is likewise well exemplified in the case of those organs and structures of the body which subserve important ends during foetal life, but which, ceasing to be necessary after birth, undergo a sort of natural atrophy, such as the thymus gland, and certain vessels specially concerned in the foetal circulation. The uterus after parturition undergoes a certain amount of atrophy, and the ovaries, after the child-bearing period, become, shrunken. Atrophy of a part may also be caused by interruption to its normal blood supply, as in the case of the ligature or obstruction of an artery. Again, long standing disease, by affecting the nutrition of an organ and by inducing the deposit of morbid products, may result in atrophy, as frequently happens in affections of the liver and kidneys. Parts that are subjected to continuous pres sure are liable to become atrophied, as is sometimes seen in internal organs which have been pressed upon by tumours or other morbid growths, and is well illustrated in the case of the feet of Chinese ladies, which are prevented from growing by persistent compression exercised from birth. Atrophy may manifest itself simply by loss of sub stance ; but, on the other hand, it is often found to co-exist with degenerative changes in the textures affected and the formation of adventitious growth, so that the part may not be reduced in bulk although atrophied as regards its proper structure. Thus, in the case of the heart, when affected with fatty degeneration, there is atrophy of the proper muscular texture, which, however, being largely replaced by fatty matter, the organ may undergo no diminution in volume, but may, on the contrary, be increased in size. Atrophy is usually a gradual and slow process, but some times it proceeds rapidly. In the disease known by the 