THE EAR. 767 



1845, p. 102; Virchow, "Notiz Uber den Glaskorper," in "Arch. f. 

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

 Wurzb. phjs. med.," Gesellsch., IL, p. 317. LENS: W. Werneck, 

 " Mikr. Betracht. der Wasserhaut u. des Linsensystems," in Ammon's 

 " Zeitsch.," Bd. IV. and V. ; R. Hannover, " Beobachtungen iiber den 

 Bau der Linse," in Mull. "Archiv," 1845, p. 478; Harting, " His- 

 tolog. Anteekennigen," 1846, pp. 1-7, and " Recherch. microme'triques." 

 DEVELOPMENT or THE EYE : H. Scholer, " De oculi evolutione," Mitav., 

 1849, Diss. ; Remak, in his large work, " Ueber Entwicklungsge- 

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

 optic nerve," in "Phil. Trans.," L, 1850; Henle, "De membr. pupil- 

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

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

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

 which, see Arnold, " Org. sensuum." 



IL OF THE ORGAN OF HEARING. 



232. The auditory organ consists of the proper sentient parts with 

 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 auris], J-l line thick, and while retaining the thick 

 pericJiondrium 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 cartilages, though it is distin- 

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

 line in diameter, in the striated matrix. 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 J-l 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 ceruminosce, hairs and sebaceous follicles in a dense subcu- 

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



