THE EAR. 767 



1845, p. 102; Vircliow, "Notiz liber den Glaskorpcr," in " Arcli. f. 

 path. Anatomic," IV., p. 468 [and V. 2, p. 298], and in " Verb. d. 

 WiJrzb. pbys. med.," Gesellsch., II., p. 317. Lens : W. Werneck, 

 " Mikr. Betracht. der Wasserbaut u. dcs Linsensysteras," in Amnion's 

 " Zeitscb.," Bd. IV. and V. ; R. Hannover, " Beobacbtungen iiber den 

 Ban der Linsc," in Mlill. "Arcbiv," 1845, p. 478; Ilarting, " His- 

 tolog. Anteekennigen," 1846, pp. 1-7, and " Rechercb. micromdtriques." 

 Development of the Eye : II. Scboler, " De oculi evolutione," Mitav., 

 1849, Diss. ; Remak, in bis largo work, " Uebcr Entwicklungsge- 

 schicbte," 1850-51; Gray, "On the development of the retina and the 

 optic nerve," in "Phil. Trans.," I., 1850; Henle, "De raembr. pupil- 

 lari," Bonn., 1832; Reich, " De membr. pupillari," Berolini, 1833; J. 

 Muller, also Arnold, and Ilenle, on the "M. capsulo-pupill.," in Am- 

 mon's "Zeitscb.," II., p. 391, III., p. 37, IV., pp. 23 and 28. Besides 

 which, see Arnold, " Org. sensuum." 



II.— OF THE ORGAN OF HEARING. 



§ 232. The auditory organ consists of the proper sentient parts vf'ith. 

 the expansion of the acoustic nerve, which are contained in the osseous 

 substance of the labyrinth ; and of special accessory apparatus, the 

 external and middle ear, intended chiefly for the reception and conduc- 

 tion of the undulations of sound. 



§ 233. External and middle ear. — The auricle [pinna) and the car- 

 tilaginous external auditory canal, are supported by the cartilage of the 

 ear {cartilago anris), \-\ line thick, and while retaining the thick 

 pericliondrium very flexible, but otherwise extremely brittle, and the 

 form of which is well known. This cartilage.^ in its more intimate struc- 

 ture, approaches the yellow or reticular cai'tilages, though it is distin- 

 guished by a considerable preponderance of cartilage-cells, O'Ol of a 

 line in diameter, •in the striated viatrix. It is covered by the external 

 integument, which, except in the lobule, contains no fat and on the con- 

 cave side of the auricle is closely adherent to the cartilage, where it is 

 characterized by a great abundance of glands. These are, in the first 

 place, common sebaceous follicles, which are most developed in the concha 

 and fossa scaphoidea, where they attain the diameter of ^-1 line ; 

 secondly, minute sudoriparous glands of 1-16 of a line on the convex 

 side of the pinna ; and, lastly, the ceruminous glands, already described 

 (§ 71, 72), in the cartilaginous, external auditory canal itself. In 

 the latter, the cutis measures 1-5-1-8 of a line in thickness, without the 

 epidermis, which is 1-75-1-50 of a line thick ; and presents, besides the 

 glandulce cerwninosce, hairs and sebaceous follicles in a dense subcu- 

 taneous tissue, whilst in the osseous part of the passage it is very thin, 



