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LEFT ANZAC 202 APE products of digestion are expelled. With regard to its anatomy, it is sufficient to state that it is kept firmly closed on ordinary occasions by the external and internal sphincter muscles, the former of which contracts the integument around the opening, and, by its attachment to the coccjrx behind, and to a tendinous center in front, helps the levator ani muscle in supporting the aperture dur- ing the expulsive efforts that are made in the passage of the faeces or intestinal evacuations; while the latter, or internal sphincter, is an aggregation of the cir- cular muscular fibers of the lowest part of the rectum, and acts in contracting the extremity of the tube. The integu- ment around the anus lies in radiating plaits, which allow of its stretching with- out pain during the passage of the faeces; and the margin is provided with a num- ber of sebaceous glands. ANZAC, a name applied to Austra- lian and New Zealand troops in the World War and made up of the first letters of their title, "Australian and New Zea- land Army Corps." AONIA (a-6'ne-a), in ancient geogra- phy a name for part of Bceotia in Greece, containing Mount Helicon and the foun- tain Aganippe, both haunts of the muses. AORIST, the name given to one of the tenses of the verb in some languages (as the Greek) which expresses indefinite past time. AORTA, the largest artery in the hu- man body, and the main trunk of the arterial system itself. It takes its de- parture from the upper part of the left ventricle of the heart, whence it runs upward and to the right, at that part of its progress being called the ascending aorta; then it turns to the left, passes the spinal column, and bending down- ward forms the arch of the aorta. Con- tinuing its course along the left of the spine, it is called the descending aorta. Passing through the aperture in the dia- phragm into the abdomen, it becomes the abdominal aorta. Finally, it bifurcates about the fourth pair of lumbar vertebrae, and forms the two primitive iliac ar- teries. Upward from the heart the rami- fications are numerous and exceedingly important. The aorta has three valves called the sigmoid or semi-lunar valves, to prevent the reflux of the blood into the heart. AOSTA (a-os'ta), a cathedral city of Italy, on the Dora Baltea, 19 miles from the opening of the great St. Bernard Pass, and 80 miles N. N. W. of Turin by rail. It is surrounded by rich or- chards, vineyards, and almond planta- tions. It is the ancient Augusta Prae- toria; and several monuments of the Roman times still remain. St. Bernard was Archdeacon of Aosta; and here Anselm, Archbishop of Canterbury, was born. Near by are the celebrated baths and mines of St. Didier. The beautiful valley of Aosta is rich in woods, pastures, minerals, and mineral walls. French is generally spoken. Pop. about 7,000. AOUDAD, the ammotrogus tragelaphus, a remarkable species of sheep, with cer- tain affinities to the goats. It is of a reddish-brown color, with much long hair hanging down from the front of the neck and the base of the forelegs. It has long, powerful horns, and is fierce in character. It inhabits mountainous re- gions in Abyssinia and Barbary. APACHES (ap-a'chez), a tribe of North American Indians, formerly very fierce and numerous, living in portions of Texas, New Mexico, and Arizona, and belonging to the Athabascan family. Long after the annexation of their ter- ritory by the United States they con- tinued their raids in spite of severe de- feats. An attempt made by the United States Government to confine the Apaches within a reserved territory in Arizona led to bloodshed in 1871, About 300 now occupy a reservation at Fort Sill, Okla. Their total number is about 5,000. APARTMENT HOUSE, a structure built to accommodate a number of fam- ilies each in its own set of rooms, which form a separate dwelling with an en- trance of its own. The term is chiefly used in the United States, though houses of this kind have long been built in Europe. APATITE, a translucent but seldom transparent mineral. It passes through various shades of color, from white to yellow, green, blue, and occasionally red. It is now largely utilized as a source of artificial phosphate manures. APE, a common name of a number of quadrumanous animals inhabiting the Old World (Asia and the Asiatic islands, and Africa), and including a variety of species. The family includes the chim- panzee, gorilla, orang-outang, etc., and has been divided into three genera, trog- lodytes, simia, and hylobates. The highest and most man-like mon- keys, including gorilla, chimpanzee, orang-outang, gibbon, and several other species, are called Anthropoid Apes. They are all arboreal, and inhabit Africa, southeastern Asia, and the Malay Archi-