Anacon´da, the popular name of two of the largest species of the serpent tribe, viz. a Ceylonese species of the genus Python (P. tigris), said to have been met with 33 feet long; and Eunectes murīnus, a native of tropical America, allied to the boa-constrictor, and the largest of the serpent tribe, attaining the length of 40 feet. They frequent swamps and rivers, are without poison fangs, and kill their victims by constriction.
Anaconda, a town of the United States, Montana, with the largest copper-smelting works in the world. Pop. (1920), 11,668.
Anac´reon, an amatory lyric Greek poet of the sixth century B.C., native of Teos, in Ionia. Only a few fragments of his works have come down to us; the collection of odes that usually passes under the name of Anacreon is mostly the production of a later time, the poetry of the real Anacreon being much less frivolous.
Anadyom´ĕnē (Gr., 'she who comes forth'), a name given to Aphroditē (Venus) when she was represented as rising from the sea, as in the celebrated painting by Apelles, painted for the temple of Æsculapius at Cos, and afterwards in the temple of Julius Caesar at Rome.
Anadyr (a˙-nä´dēr), the most easterly of the larger rivers of Siberia and of all Asia; rises in the Stanovoi Mountains, and falls into the Gulf of Anadyr; length, 600 miles.
Anæ´mia (Gr., 'want of blood'), a medical term applied to an unhealthy condition of the body, in which there is a diminution of the red corpuscles which the blood should contain. The principal symptoms are paleness and general want of colour in the skin, languor, emaciation, want of appetite, fainting, palpitation, &c.
Anæsthe´sia, or Anæsthe´sis, a state of insensibility to pain, produced by inhaling chloroform, or by the application of other anæsthetic agents.
Anæsthet´ics are medical agents chiefly used in surgical operations for the abolition of pain. They are divided into (1) general anæsthetics, those in which complete unconsciousness is produced; (2) local anæsthetics, those which act upon the nerves of a limited area alone.
The earliest record of attempts to produce anæsthesia is to be found in the thirteenth century. Since then many agents have been tried. The first scientific effort was in 1800, when Sir Humphry Davy experimented with nitrous oxide, but without practical result. In 1844 Wells, an American dentist, used nitrous oxide, also without result. In 1846 Morton, another American dentist, used ether, and from that time it was increasingly used in America. In the same year the first operation under ether was performed in University College Hospital, London. In 1847 Sir James Simpson (Edinburgh) introduced chloroform. Through his influence it was soon largely used throughout England and Scotland, and continued to be the chief anæsthetic till about the end of the nineteenth century, when ether again became popular in England. To-day, in England, as always in the United States, ether is the most widely-used anæsthetic. Much controversy exists regarding the respective merits of ether and chloroform. The general opinion is, that ether is on the whole safer, but more liable, in the British climate, to be followed by bronchitis; while there are various conditions when chloroform is still preferable. They are frequently combined in use. Nitrous-oxide gas (laughing gas) is much used in dentistry. Lately, nitrous oxide has been used with ether; while ether and oxygen together were
much used with the British Expeditionary Force in France during the European War (1914-8). The administration of all anæsthetics is helped when the patient is given a hypodermic injection of morphia shortly before. Twilight sleep, increasingly used in childbirth, is the production of a partial anæsthesia by the administration of scopolamin morphine. Local anæsthetics are much used in minor surgery, and with proper technique act effectively. Cocaine was the first of these, and is still widely used. Of later developments, eucaine and novocaine are best known. Spinal anæsthesia is the injection of stovaine or similar substance into the spinal cord, producing anæsthesia of a large part of the body, varying according to the site of the injection.