AUDITORY ORGAN. 377 



ducts are lined with a double layer of epithelial cells. Tin- 

 cells throughout the whole gland show a cuticular border on 

 the side toward the lumen. These glandular tubules are dis- 

 tinguished from sweat glands by their wide lumena, and by 

 the fact that the gland cells contain granules of different kinds. 

 Of these, the most numerous are yellowish-brown pigment 

 granules. Other granules resemble fat in their action toward 

 osmic acid, although their other properties do not correspond 

 with this (Schwalbe). These coil glands open in the newborn 

 into the hair follicles. In the adult, on the contrary, their 

 orifices are on the free skin surface near the hair follicles 

 (Alzheimer). 



The cerumen or wax consists of a secretion of the coil glands 

 (fat droplets and pigment granules), together with hairs and 

 desquamated epithelial cells. 



The cartilage of the external meatus is elastic like that of 

 the auricle. 



The blood-vessels of the ear drum are derived partly from the 

 vessels of the tympanic cavity, and partly from those of the 

 external meatus. Here two vascular networks can be dis- 

 tinguished, the inner of which lies under the stratum rnucosum, 

 while the outer is situated between the epidermis and the 

 lamina propria. Each of these networks surrounds the handle 

 of the malleus,, and forms a ridge around the border of the 

 tympanic membrane. The vessels of the central part and those 

 of the edge of the membrane are thus connected. Venous 

 vessels of both plexuses anastomose with one another by means 

 of perforating branches (Moos). The lymph-vessels of the 

 ear drum have an arrangement similar to that of the blood- 



O 



vessels. Fine networks of nerves have been found in this 

 region. 



4. OLFACTORY ORGAN. 



Having in view the structure of the nasal mucous membrane, 

 the nasal cavity may be divided into three regions : 



(1) The regio vestibularis ; 



(2) The regio respiratoria ; and 



(3) The regio olfactoria. 



