354 THE SECRETIONS: 



Cerumen. 



The glandulae ceruminosae, which are situated in the external 

 skin of the meatus auditorius externus, secrete the ear-wax 

 (cerumen), a peculiar salve-like matter, which is thrown out as a 

 yellowish milk. 



If a small portion of ear-wax is pressed between two slips of 

 glass and observed under the microscope, we shall find a quan- 

 tity of variously-grouped lamellae lying in a tolerably homoge- 

 neous yellow mass. In these lamellae, the practised observer 

 will easily recognize pavement epithelium. On mixing the ear- 

 wax with water, which may be readily done, a sort of yellowish 

 milk is obtained, in which, with the microscope, we may observe 

 colourless fat-vesicles, epithelium- scales, and sometimes rhombic 

 crystals, very like cholesterin. The yellow colour of the cerumen 

 does not belong to the fat, but to the matter which is soluble 

 in water. Berzelius has made the following observations on the 

 cerumen. Ether takes up fat from the mass which swells in it, 

 and becomes as soft as goose-grease ; it has not an acid reaction, 

 consists of stearin and olein, and contains a substance which, 

 after saponification, gives off a strong smell of sweat. The 

 fatty acids which are liberated on the addition of hydrochloric 

 acid melt at 104. After the fat has been removed, alcohol 

 takes up a yellow substance from the ear-wax, which, on eva- 

 poration of the alcohol, is left as a glossy matter, perfectly 

 soluble in water, and of a very bitter taste. It may be en- 

 tirely thrown down from its aqueous solution by the neutral 

 acetate of lead and by chloride of tin ; on the other hand, 

 nitrate of silver does not even render it turbid; hence there 

 can be no chlorides present. Upon incinerating this mass, 

 there remains an ash, which consists of the carbonates of pot- 

 ash and lime. The portion not dissolved by alcohol yields to 

 water a small amount of yellowish matter, which is very similar 

 to the soluble matter obtained in a similar manner from the other 

 fluids of the animal body, and has a piquant taste ; but it is 

 distinguished by the circumstance that neither lime-water, basic 

 acetate of lead, bichloride of mercury, nor tannic acid preci- 

 pitate it. 



The portion of the ear-wax which is insoluble in ether, 



