Ear
2 of the 7 encyclopedias on this shelf carry an entry for Ear. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
the organ of hearing; is composed of three parts, the external ear, the middle ear, or tympanum, and the internal ear, or labyrinth. The external ear consists of two portions, the auricle or pinna (the part popularly recognized as the ear), and the auditory canal or external meatus. In man, the auricle, on its outer or more exposed surface, presents various eminences and depressions, resulting from the form of its cartilaginous frame-work. The deep, capacious central space to which several grooves converge is termed the concha, and the lowest and pendulous portion of the ear is termed the lobe. The auditory canal passes from the concha inward and a little forward for rather more than an inch. It is narrower at the middle than at either extremity; and on this account there is often considerable difficulty in extracting foreign bodies which have been inserted into it. The membrane of the tympanum or drum which terminates it is placed obliquely, in consequence of the lower surface of the meatus being longer than the upper. The canal is partly cartilaginous and partly osseus; the osseus portion consisting, in the fœtus, of a ring of bone, across which the membrane is stretched, and in many animals remaining persistently as a separate bone. The orifice of the meatus is concealed by a pointed process, which projects from the facial direction over it like a valve, and which is called the tragus, probably from sometimes being covered with bristly hair like that of a goat (tragus); and it is further defended by an abundance of ceruminous glands, which furnish an adhesive, yellow, and bitter secretion, the cerumen or wax, which entangles small insects, EAGLE Top-Harpy Eagle Bottom-Kite particles of dust, and other small foreign bodies, and prevents their farther passage into the meatus. The middle ear, or cavity of the tympanum, is a space filled with air which is received from the pharynx through the Eustachian tube and traversed by a chain of very small movable bones, which connect the membrane of the tympanum with the external ear. It lies, as its name implies, between the external meatus and the labyrinth or internal ear, and opens posteriorly into the cells contained in the mastoid portion of the temporal bone, and anteriorly into the Eustachian tube. The cavity is of an irregular shape, and is lined by a very delicate ciliated epithelium, which is a prolongation of that of the pharynx through the Eustachian tube. Its external wall is in great part formed by the membrane of the tympanum, which is nearly oval, and placed in a direction slanting inward, so as to form an angle of about 45° with the angie floor of the auditory canal. The Eustachian tube, into which the tympanic cavity opens anteriorly, is about an inch and a half in length, and passes downward, forward, and into its opening in the pharynx. It is partly osseus but chiefly cartilaginous, and allows the free passage of air in and out of the tympanum. The internal ear or labyrinth is the essential part of the organ of hearing, being the portion to which the ultimate filaments of the auditory nerve are distributed. It is composed of three parts: the vestibule, the semi-circular canals, and the cochlea, which form a series of cavities presenting a very complicated arrangement, and and lying imbedded in the hardest part of the petrous portion of the temporal bone. They communicate externally with the tympanum through the fenestra ovalis, and the fenestra rotunda; and internally with the internal auditory canal, which conveys the auditory nerve from the cranial cavity to the internal ear. The very dense bone immediately bounding these cavities is termed the osseous labyrinth, to distinguish it from the membranous labyrinth, which lies within a portion of it. The cochlea, so-called from its resemblance to a common snail-shell, consists of an osseous and gradually tapering canal, about an inch and a half in length, which makes two turns and a half spirally around a central axis, termed the modiolus, which is perforated at its base for the entrance of the filaments of the cochlear portion of the auditory This spiral canal gradually dinerve. minishes toward the apex of the cochlea. At its base it presents an opening into the vestibule, partially divided into two. In the infant state, one of these openings (scala tympani) does not communicate with the vestibule, but is closed by the membrane of the fenestra rotunda. Its interior is sub-divided into two passages (scale) by an osseous lamina. This is the lamina spiralis, which incompletely divides the cochlea into an upper passage, the scala vestibuli, and a lower one, the scala tympani-that is, the division is incomplete so far as the skeleton goes, but is completed during life by the lamina spiralis membranacea (or basilar membrane).
Aiton's Encyclopedia (1910)
the organ of hearing. In its simplest form, as seen in some of the lower animals, the ear is simply a sac of liquid, in which the end of the auditory nerve is expanded. The ears of the locust are situated on each side of the basal joint of the abdomen. The green grasshoppers and katydids hear through ears situated on their front legs. These ears look like little scars. The mosquito is believed to hear through sensitive spots on its antennae or feelers. The human ear is rather complex. It consists of three divisions,-the outer, or external ear, the middle ear, and the inner ear, or labyrinth. The peculiar folds and passages of the outer ear are of service in catching sound, and in enabling the hearer to determine in what direction it comes from. The middle ear is an air chamber , communicating with the throat by an air passage or tube, called the eustachian tube. The ear chamber is separated from the outer and from the inner ear by membranes giving it the structure of a drum. Three small, movable bones, called the bones of the ear, reach from the outer membrane to the inner. The inner ear, or labyrinth, is filled with liquids. The auditory nerve, which comes from the brain, terminates here. Sound reaches the brain as follows. The vibrations of the atmosphere set the outer membrane in motion. This agitates the bones of the ear. They set up a vibration in the inner membrane, which, in turn, shakes the liquids in the labyrinth, thus disturbing the ends of the auditory nerve, along which the sensation flies to the brain. A forceful vibration gives the impression of a loud noise. If agreeable vibrations come frequently, they give the impression of music. The human ear is able to note a sound having a frequency of from 32 to 38,000 vibrations per second. A rare ear can go to 50,000. The ear of a cat is capable of hearing an extraordinarily high note. No doubt the world, especially the insect world, is full of sounds quite intelligible to many ears, but unknown to the human ear. The linings and the membrane of the outer ear are kept moist by the excretion of ear wax. When, as often happens, especially in old age, the membrane becomes dry and inflexible, and thus unable to vibrate, partial or entire deafness ensues. In case of defective hearing an ear trumpet is often used to collect the sound waves and thus increase their intensity. See Sound ; Deaf Mutes