aisthēsis, feeling, sensibility), or Analgesia. A loss of sensibility to external impression. An- æsthesia means, properly, the loss of the sense of touch; analgesia, the loss of the sense of pain. The terms are often used interchangeably, and anæsthesia has come to mean the loss of sensi- bility to all kinds of sensory impressions. Tac- tile, pain, heat, cold, and muscular senses are those usually affected. All these sensations are received by special sense organs situated on the outside of the body or in mucous membranes. From the sensory end organs the paths for these sensations pass into the spinal cord, and thence up to more or less distinct areas of the brain. Disease or injury in any part of the path may produce a loss of these sensations. Thus, if a nerve which contains sensory fibres is injured, the parts whose sensory nerves are detached from the brain lose all sensibility. In certain diseases of the spinal cord the sensory fibres are affected, and all parts below the site of the morbid process lose their sensibility. In a certain rare disease (syringomyelia), there is loss of pain sense and of the sense of heat and cold, but not of tactile sense. Should accident or disease occur still higher up in the sensory area of the brain, or in areas where sensory fibres come together, as in the medulla and internal capsule, one side of the entire body may become anæsthetic. Such ex- treme grades of anæsthesia are infrequent, but there is almost no area in the body which may not lose its sensibility by accident or disease. Even in "functional" diseases, as hysteria, in which no known changes have taken place in the nervous tissues, loss of sensibility may occur. Certain drugs, which, when locally applied, or taken into the body, produce similar diminution or loss of sensibility, are termed anæsthetics. See Anæsthetic; Sensation.
AN'ÆSTHET'IC (for derivation, see Anæsthesia). Any remedy used to relieve pain or other hyperæsthetic conditions of the sensory nerves. Those that relieve pain alone are frequently termed analgesics. The broader term is used indiscriminately, including two great groups
of anæsthetics: (1) Local anæsthetics, affecting
a restricted area; (2) general anæsthetics, tem-
porarily affecting the sensibility of the entire
body. Cold is one of the safest local anæsthet-
ics, in the form of cold water or cracked ice.
Various freezing mixtures, such as ether spray
or ethyl chloride spray, are even more valuable,
but require skill and experience in use, or the
part may be frozen and thus injured. Carbolic
acid and its allies, creosote, thymol, and other
volatile oils, containing phenol-like bodies, are
powerful anæsthetics. These, when applied local-
ly, have the power of paralyzing the sense or-
gans of the skin aid mucous membranes. Their
use is attended with danger, however, and should
be administered by a physician only. The most
important of the local anæsthetics is cocaine
(q.v.), which has the peculiar and useful prop-
erty of being able to paralyze sensory nerves
alone. In a weak solution, it is injected under
the skin, which it renders anæsthetic, relieving
pain, as in neuralgia, and permitting operations
on the part. Applied to the mucous membrane,
it destroys all feeling, and can be used in the
eye, ear, nose, mouth, rectum, vagina, urethra,
and bladder, to overcome pain or permit oper-
ations. Dr. J. Leonard Corning, of New York,
in 1885, discovered that when injected in weak
solution into the spinal canal, it produced a loss of all sensation below the place of injection. Extensive operations have been performed under cocaine, and children have been born without pain to the mother; but there are some serious disadvantages in this medullary narcosis. Eucaine, holocaine, and orthoform have been used for the same purpose as cocaine.
It is probable that for thousands of years the natives of India have used Indian hemp for the relief of pain, while the inhabitants of China have used opium from the poppy plant. In all ages and among all peoples, as far back as history records, people have used alcoholic drinks to produce diminished sensibility to pain. Within recent years the pharmaceutical chemist has been industrious in making new compounds to relieve pain. There are scores of such substances now in use, among which are acetanilid (q.v.), antipyrine (q.v.), methacetine. phenacetine (q.v.), thallin, phenetidin, phenocoll, and salocoll.
In 1800, Sir Humphry Davy, experimenting with nitrous oxide (q.v.) or laughing-gas, suggested its usefulness as an anæsthetic. In 1844, Dr. Horace Wells (q.v.). an American dentist, demonstrated that the gas may be actually employed for painless extraction of teeth. In 1828, Dr. Hickman suggested carbonic acid gas. As early as 1795, Dr. Pearson had used the vapor of sulphuric ether for the relief of spasmodic affections of the respiration. The fact that sulphuric ether could produce insensibility was known to Faraday in 1818, and was shown by the American physicians, Godwin (1822), Mitchell (1832), Jackson (1833), Wood and Bache (1834); but it was first used to prevent the pain of an operation by Dr. Crawford W. Long (q.v.), of Georgia, who removed a tumor from a patient under ether in 1842. Unfortunately, Long did not publish his discovery to the medical world, and failed to utilize his opportunity. Upon the suggestion of Dr. Jackson, Dr. W. T. G. Morton (q.v.). a dentist of Boston, after experimenting privately, introduced ether anæsthesia into general use in 1846. At the request of Dr. John C. Warren, Morton administered ether in an operation at the Massachusetts General Hospital on October 16, 1846. The fiftieth anniversary of this event was celebrated in Boston on October 16, 1896. In December, 1846, Robinson and Liston, in England, operated on patients rendered insensible by the inhalation of ether vapor. This substance was extensively used for a year, when Sir J. Y. Simpson, of Edinburgh, discovered the anæsthetic powers of chloroform (see Chloroform), and introduced the use of it into his own department, midwifery. Since that time, chloroform has been the anæsthetic in general use in Europe; but ether is preferred in America, except for children and parturient women. Chloroform should not be given where there is weak action of the heart from disease. No anæsthetic should be given in case of chronic or severe kidney disease. Consult Probyn-Williams, Guide to Administration of Anæsthetics (New Y'ork, 1901).
ANAGAL'LIS. See Pimpernel.
ANAGNI, a-nii'nye.
An episcopal city in South Italy, situated on a hill 36 miles southeast of Rome (Map: Italy, H 6). Four popes were born here, and four, Gelasius II., Adrian IV., Alexander III., and Boniface VIII., sought refuge here from persecution, while many noble Italian
