GLANDS. 427 



CERUMINOUS GLANDS. 



The cemminous glands are situated beneath the integu- 

 ment of the deeper part of the external meatus of the ear. 

 They occur mixed up with numerous sebaceous glands, but 

 have no direct communication with these, as they open on the 

 surface by distinct apertures. 



They resemble very closely in structure the sudoriferous 

 glands just described, consisting, like them, of convoluted 

 and looped tubes, which unite together and end in a single 

 slender duct. They differ, however, from the sudoriferous 

 glands in the fragile character of the tubes, which renders it 

 somewhat difficult to procure a perfect preparation of one of 

 them ; this difference seems to arise principally from the ab- 

 sence, in a great measure, of fibrous tissue, whereby, in the 

 sudoriferous glands, the tubes are bound together, as well as 

 of also enveloping plexuses of blood-vessels. (See Plate LVII. 

 fig. 5.} 



In the external ear of the sheep, in which these glands 

 may be studied to great advantage, the tubes appear of a pale 

 straw colour, transparent and glossy, with but few apparent 

 granular cells, and these totally different from the character- 

 istic cells of the sebaceous glands, filled with innumerable 

 globules of oil. The granular cells filling the tubes, and 

 which are usually concealed by a quantity of oily fluid, may 

 be made apparent by the addition of acetic acid. The mem- 

 brane of the tubes is composed of a nucleated form of elastic 

 tissue. * 



From the fact of the ceruminous glands coexisting with 

 numerous sebaceous glands, it seems probable that the ceru- 

 men is the mixed production of the two descriptions of glands. 



KIDNEYS. 



The substance of the kidney, like that of the other large 

 glands, may be divided, for the purposes of description, into 

 two orders or systems of structure or apparatus : the glan- 



* It seems doubtful, after all, whether the ceruminous are any thing 

 more than a variety of the sudoriferous glands. 



