Page:The American Cyclopædia (1879) Volume VI.djvu/360

 352 EAR sacs receive the nervous filaments, and are thus connected with the serous membrane lining the labyrinth, but everywhere else they are free, and separated from it by the perilymph, while their cavities contain a similar fluid called endolymph. In the vestibular portion is found a crystalline powder, proved by chemical ex- periment to be carbonate of lime, and denom- inated otolithea; the office of this is supposed to be to communicate the vibrations to the nervous surfaces. The filaments of the audi- tory nerve terminate by loops, or minute points, in the sacculus, the utriculus, the ampulla of the membranous semicircular canals, and the membranous lamina which divides the cochlea. In the process of hearing, the vibrations of the atmosphere, caused, we will say, by touching one. of the keys of a piano, pass toward the external ear, where they are collected and concentrated by its peculiar form and struc- ture; thus concentrated, they pass along the canal to the tympanum, where they produce a vibration ; this vibration is communicated by the chain of bones to the membrane covering the foramen ovale, by which it is passed to the fluid contents of the vestibule and to the sacs, and thus- reaches the nervous surface, which is expanded over the whole labyrinth, and pro- duces the sensation of sound. The internal and middle ear are situated wholly within the temporal bone, which is here much thicker and harder than elsewhere, in order to protect the delicate and complicated structure from injury. In the article DEAF AND DUMB we have spoken in general terms of the causes which induce deafness ; but we may say here that while congenital deafness is usually the result of deficiency or malformation of some portion of the organ, thus preventing the trans- mission of the vibration or sound wave, acci- dental deafness usually arises from mucous secretions, the result of inflammation, clogging or thickening the membranes of the middle ear, or liberation attacking the little bones and causing their discharge ; inflammation of the serous membrane of the labyrinth; or paralysis of the auditory nerve. As may be supposed, the cure of complete deafness is ex- ceedingly rare. The sense of hearing, like most of the senses, is capable of a much high- er cultivation than is generally given to it. The blind, to whom touch and hearing make up in part for the loss of vision, acquire re- markable powers of hearing. They will hear a footstep or the opening of a door at a dis- tance at which ordinary persons cannot dis- tinguish a sound. In some brain affections ithere is more or less morbid sensitiveness of hearing ; and in that condition of the nervous system brought on by long continued and in- tense excitement, and which often terminates in insanity, the same phenomenon is observed. The form of the external ear varies mate- rially in different races of men, and still more in the animal tribes. In the Caucasian race it is of moderate size, well formed, and neither EARL very prominent nor pressed closely to the head. In the Malay and Mongolian it is large, ill- proportioned, the lobe naturally long, and the whole ear standing out prominently; in the Indian race the conformation is similar to the Mongolian, though less prominent ; in the negro the ear is flat, broad, and adheres so closely to the head as to give the idea of hav- ing been fastened there by a bandage. Of the inferior animals, the mammalia only have an external ear; in birds it is merely a small orifice ; in fishes, when it exists, it is covered by the skin, as it is also in reptiles. The va- riety in its form in mammals extends even to different varieties of the same animal. The drooping ear of the King Charles and other spaniels contrasts forcibly with the erect prom- inent ear of the foxhound and the Esquimaux dog; and both differ greatly from the short open ear of the bulldog. The horse has a sen- sitive and well formed ear, though of small size ; while the ass, with no better powers of hearing, is supplied with long aural appendages which seem most adapted for fans. The ele- phant has a small ear as compared with his great size, though the flap of skin which pro- tects it is of considerable dimensions. The carnivora generally have small but very quick ears, and they usually possess erectile power, which enables them to throw them into shapes in which they will most readily catch the sound wave. The mole, though his ear is hardly discernible in the fine fur which covers it, is yet very quick of hearing. Of all the mammals, the bat tribe possess the largest ears in proportion to the size of their bodies, the phyllostomus and the megadenus in par- ticular being provided with these appendages so large as to form nearly one third of the su- perficial extent of their bodies. Among savage and half- civilized tribes the idea prevails that the lengthening of the lobe of the ear by heavy ornaments, and the enlargement of the perfo- rations made for attaching them, both add greatly to the beauty of the wearer. In the Burmese statues of Gaudama he is represented in a sitting posture, and the lobes of his ears extend to the level of his lap. Among the African tribes the perforation in the ear is en- larged so that a stick an inch or more in diam- eter may be thrust through it, and some of them use the ear instead of a pocket to carry small articles. EARL, the most ancient title of nobility used in Great Britain. Under the early Saxon kings the powerful nobles to whose charge shires or territories had been committed were called ealdormen, literally elder men (whence the modern alderman), a term equivalent to the Latin senior or senator, and given in Latin documents as princeps, dux, or comes. The Danes subsequently applied the term eorle, which signified orig'inally a man of noble birth, as opposed to the ceorl or churl, to the same men who had borne the title of ealdormen. The Saxon earl derived his title solely from his