OF THE GLANDS OF THE SKIN. 209 



Phys.," tab. XVL, fig. 9 ; F. Arnold, " Icon. Org. Sens.," tab. XL, 

 and my own " Mikr. Anat.," tab. I. 



B. OF THE CERUMINOUS GLANDS. 



§ 71. The ceruminous glands of the JEar are brownish simple glands, 

 in external appearance precisely similar to the sudoriparous glands, which 

 do not exist in the whole external auditory meatus, but only in its car- 

 tilaginous portion, where they are situated between the lining membrane 

 of the passage and the cartilage, or the fibrous substance which supplies 

 its place, in a tough subcutaneous tissue, containing little fat. They 

 form a connected yellowish-brown layer, visible enough to the naked 

 eye, which is thickest in the inner half of the cartilaginous meatus, and 

 becomes gradually thinner and more lax externally, extending, however, 

 quite as far as the cartihiginous meatus itself. Each ceruminous gland 

 consists of a glandular coil and an excretory duct. The former (Fig. 

 83 d), To~5~4 of ^ l'>^6 in size, is formed by the multitudinous convolu- 

 tions of a single canal of 0'03-0-06 on the average 0*04-0*05 of a line in 

 thickness, which occasionally, although not constantly, throws out little 

 diverticula, and terminates in a blind slightly enlarged end. From the 

 coil a short straight excretory duct, 0"0l7-0-024 of a line thick, passes 

 perpendicularly upwards, penetrates the corium and epidermis of the 

 auditory meatus, and usually opens independently in a circular pore of 

 0"04-4 of a line, or else into the upper part of a hair-sac. 



The following is the intimate structure of the ceruminous glands. 

 The canals of the coil present a fibrous coat, and an epithelium, the 

 former being 0-004-0-005, the latter 0*004 of a line in thickness. The 

 fibrous covering presents exactly the same conditions as in the larger 

 sudoriparous glands, that is, it consists of an internal longitudinal layer of 

 smooth muscles, 0-0023-0-0026 of aline in diameter, and an external layer 

 of connective tissue, with scattered nuclei, and occasionally very fine trans- 

 verse nucleus-fibres. The epithelium rests immediately upon the mus- 

 cular layer, and consists of polygonal cells of 0-006-0"01 of a line in a 

 single layer, which contain a greater or smaller number of yellowish- 

 brown pigment-granules, of immeasui'able minuteness, insoluble in acids 

 and alkalies in the cold, or whitish fat-globules up to 0-001 of a line in 

 size, and which are so disposed that the whole lengths of a gland con- 

 tain generally only one and the same kind of granules ; whence it arises 

 that they appear either uniformly brownish or opaque (by reflected light 

 whitish). The contents of the glandular canals are sometimes a clear 

 fluid, sometimes a granular substance composed principally^ of cells ana- 

 logous to those of the epithelium, whence it would seem that the same 

 kind and mode of secretion occurs in them as in the sudoriparous glands. 

 The excretory ducts possess a coat of connective tissue, and an epi- 

 thelium consisting of several layers, and constituted of small nucleated 



14 



