364 SECRETION. 



with the secretion of sebaceous glands connected with the short hairs in this situation. 

 It is difficult to ascertain what share these two sets of glands have in the formation of 

 the cerumen. Robin is of the opinion that the waxy portion of the secretion is produced 

 entirely by the sebaceous glands, and that the convoluted glands, commonly known as the 

 ceruminous glands, produce a secretion like the perspiration. He calls the latter, indeed, 

 the sudoriparous glands of the meatus. This view is, to a certain extent, reasonable ; 

 for the sebaceous matter is not removed from the meatus by friction, as in other situa- 

 tions, and would have a natural tendency to accumulate. But the contents of the ducts 

 of the ceruminous glands differ materially from the fluid found in the ducts of the ordi- 

 nary sudoriparous glands, containing granules and fatty globules, such as exist in the 

 cerumen. Although the glands of the ear are analogous in structure, and, to a certain 

 extent, in the character of their secretion, to the sudoriparous glands, the fluid which they 

 produce is peculiar. We shall see, also, that the perspiratory glands of the axilla and of 

 some other parts produce secretions differing somewhat from ordinary perspiration. As 

 far as can be ascertained, the cerumen is produced by both sets of glands. The sebaceous 

 glands attached to the hair-follicles probably secrete most of the oleaginous and waxy 

 matter, while the so-called ceruminous glands produce a secretion of much greater fluid- 

 ity, but containing a certain amount of granular and fatty matter. 



The consistence and general appearance of cerumen are quite variable within the lim- 

 its of health. When first secreted, it is of a yellowish color, about the consistence of 

 honey, becoming darker and much more viscid upon exposure to the air. It has a very 

 decided and bitter taste. It readily forms a sort of emulsive mixture with water. 



Examined microscopically, the cerumen is found to contain semisolid, dark granula- 

 tions of an irregularly polyhedric shape, with epithelium from the sebaceous glands, and 

 epidermic scales, both isolated and in layers. Sometimes, also, a few crystals of choles- 

 terine are found. 



Chemical examination shows that the cerumen is composed of oily matters fusible at 

 a low temperature, a peculiar organic matter resembling mucosine, with salts of soda 

 and a certain quantity of phosphate of lime. The yellow coloring matter is soluble in 

 alcohol; and the residue after evaporation of the alcohol is very soluble in water and 

 may be precipitated from its watery solution by the neutral acetate of lead or the chloride 

 of tin. This extract has an exceedingly bitter taste. 



The cerumen lubricates the external meatus, accumulating in the canal around the 

 hairs. Its peculiar bitter taste is supposed to be efficient in preventing the entrance of 

 insects. 



Meibomian Secretion. Very little is known concerning any special properties of the 

 Meibomian fluid, except that it mixes with water in the form of an emulsion more readily 

 than the other sebaceous secretions. It is produced in small quantity, mixed with a cer- 

 tain amount of mucus and the secretion from the ordinary sebaceous glands attached to 

 the eyelashes (ciliary glands) and the glands of the caruncula lachrymalis, and smears 

 the edges of the palpebral orifice. This oily coating on the edges of the lids, unless the 

 tears be produced in excessive quantity, prevents their overflow upon the cheeks and 

 directs the excess of fluid into the nasal duct. 



Mammary Secretion. 



The mammary glands are among the most remarkable organs in the economy ; not 

 only from the peculiar character of their secretion, which is unlike the product of any 

 other of the glands, but from the great changes which they undergo at different periods, 

 both in size and structure. Rudimentary in early life and in the male at all periods of 

 life, these organs are fully developed in the adult female, only in the latter months of 

 pregnancy and during lactation. It is true that, in the female, after puberty, the mam- 

 mary glands undergo a marked and rapid increase in size ; but even then they are not 



