ORGAN OF HEARING. 



539 



or endolymph or vitreous humour of the ear. 

 (Auuula labyrinth* mernbranacei. Humor 

 vitreus auris. Fr. Vitrine auditive. Germ. 

 ]{</</ c/es hdutigen Labyrinths. Die 

 GlasJ'euchtigkeit des Ohres. This humour, 

 first distinctly pointed out by Scarpa, fills 

 exactly all the cavities of the membrane- 

 ous labyrinth, that is to say, in the human 

 ear, the common sinus, ampullae, the semi- 

 circular tubes, and saccule. Like the peri- 

 lymph, it is almost as limpid as water. In 

 the endolymph there are, as has been said, 

 always found suspended calcareous concre- 

 tions. The endolymph is ,jn birds as limpid 

 as in the Mammifera; but in reptiles it is in 

 general more dense than water and a little 

 viscid. It is viscid in all fishes, but especially 

 so in the Chondropterygenous, in which it often 

 presents itself in the form of jelly. It is also 

 very decidedly viscid in the Cephalopodous 

 Mollusca. 



The masses of calcareous matter contained 

 within the membraneous labyrinth. In the ear- 

 bulb of all animals which possess one, there 

 are found small masses of a chalky nature ; 

 in some solid, in others pulverulent. Solid 

 concretions are found in the osseous fishes, 

 and in the Chondropterygenous fishes with free 

 gills, such as the sturgeon. The chalky mat- 

 ter is in a pulverulent state in Mammifera, 

 birds, reptiles, and in Chondropterygenous 

 fishes with fixed gills. In the Batraclnan rep- 

 tiles and Cephalopodous Mollusca, the cal- 

 careous matter appears rather under a concrete 

 form. 



These calcareous masses are best known in 

 osseous fishes, in which they are hard but 

 brittle bodies of a determinate shape. In 

 those animals, indeed, they have been erro- 

 neously considered as analogous to the tym- 

 panic ossicles of the higher Vertebrata. MM. 

 Breschet* and Iluschkef have lately called 

 particular attention to the subject, and have 

 described masses of calcareous matter in the 

 ear of reptiles, birds, and Mammifera. Scarpa 

 and Comparetti had observed them in the 

 human ear, without, however, detecting their 

 nature. But they had been unequivocally 

 noticed before by De Blainville ; J and pre- 

 viously to the first publication of Breschet's 

 papers on the ear in the Annales des Sciences 

 Naturelles, I had also studied them throughout 

 the animal series. 



Breschet has proposed for the solid masses 

 the name of otolithi, from ov$, auris, and ?u6o$, 

 lapis; and for the pulverulent ones that of 

 otoconia, from oi>$, and x<w? pulvis. Otoconia 

 has been translated into German by Lincke 

 Ohrsand. Huschke calls the pulverulent matter 



* Lib. cit. 



t Isis, 1834. Heft. 1. p. 107. 1833. Heft. vii. 

 p. 676. 



De 1'Organization des Animauxou Principes 

 d' Anatomic comparee, torn. i. p. 451-458. Paris, 

 1822. Also, Cours le Physiologic generale et com- 

 paree, &c. Paris, 1829. xii Le9on. p. 399. 



$ Das Gehb'rorgan, &c. s. 176. p. 203. Leipzig. 



ear-crystals, Ohrkrystalle. Krause, ear-chalk, 

 Ohrkalk. 



In the ear of man and the Mammifera in 

 general there are two masses of calcareous 

 matter; one in the common sinus and the 

 other in the saccule. According to Huschke 

 and Barruel they are composed of mucus, 

 carbonate and phosphate of lime, and some 

 animal matter. They are said to be more dis- 

 tinct in the fcetus than in the adult. From my 

 own observations I should say that they exist 

 in the human adult as distinctly as in the foetus. 

 Concretions are never found in the ampullae or 

 semicircular canals, either in man or any of 

 the lower animals. 



Examined in man and the Mammifera the 

 concretions are suspended in the endolymph, 

 and correspond to the points of the common 

 sinus and saccule where the nervous filaments 

 are implanted. 



The grains composing the calcareous mass 

 are held together by a soft mucous tissue. 



Huschke describes the grains as crystalline, 

 small six-sided columns, pointed at the ends 

 with three surfaces. They appear to me, under 

 the microscope, to have an oval form, more or 

 less elongated, in man and the mammifera, 

 passing into a spindle shape in birds and rep- 

 tiles, and, though transparent, they do not pre- 

 sent any very decided crystalline form. The 

 particles of chalk examined through the micro- 

 scope have a somewhat similar appearance, but 

 much smaller. The grains of the ear are of 

 different sizes. Of a mass which I removed 

 from the ear of a middle-aged man, the greatest 

 number had their longest diameter equal to that 

 of the globules of the human blood, that is, 

 . about the three-thousandth part of an inch. 



There is found in the cochlea of birds a mass 

 of calcareous matter. Breschet says he has 

 found, in cochleae of the human fcetus, which 

 had been dried but not macerated, small masses 

 of cretaceous matter deposited near the summit 

 of the cochlea ; and Huschke* once found, in 

 the fluid of the cochlea of a child, a collection 

 of microscopical crystals. 



Cruveilhier* asks, do the small masses of 

 cretaceous matter, found in the ear of man and 

 the mammifera, fulfil the same function as the 

 stones in the ear of fishes ? or must they be 

 considered as a remains only of a part import- 

 ant in other animals ? Breschet says, *' the 

 otolithes and otoconies have, for their use, to 

 communicate to the nervous extremities a more 

 vivid and energetic impression than a simple 

 liquid like the endolymph could do; for the 

 vibrations of a solid body are much more sen- 

 sible for their force and degree of intensity than 

 those of a liquid body." However this may be, 

 it appears that the development of these con- 

 cretions coincides, in some degree, with the 

 medium inhabited by the animal ; thus, they 

 are stony in most animals living in water, and 

 pulverulent in such as exist in air. 



The auditory or acoustic nerve. Nervus au- 



* Loc. cit. 



t Anatoinie descriptive, tome iii. p. 524. 



