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 Attruck, a river which rises in the mountains of Khorasan, and flows W. along the borders of Persia and the Russian possessions, till it falls in the south-eastern corner of the Caspian, a short distance to the N. of Ashurada.
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.
Atrium, 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
