326 SECRETION. 



coating is removed, the surface is found in a condition perfectly adapted to 

 extraiiterine existence. It is not probable that the vernix caseosa is necessa- 

 ry to facilitate the passage of the child into the world, for the parts of the 

 mother are always sufficiently lubricated with mucous secretion. 



Cerumen. A peculiar substance of a waxy consistence is secreted by the 

 glands that have been described in the external auditory meatus, under the 

 name of ceruminous glands, mixed 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. 

 According to Robin, the waxy portion of the secretion is produced entirely by 

 the sebaceous glands, and the convoluted glands, commonly known as the ce- 

 ruminous glands, produce a secretion like the perspiration. This view is to 

 a certain extent reasonable ; for the sebaceous matter is not removed from 

 the meatus by friction, as in other situations, and would have a natural ten- 

 dency to accumulate; but the contents of the ducts of the ceruminous 

 glands differ materially from the fluid found in the ducts of the ordinary 

 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 sudoripa- 

 rous glands, the fluid which they produce is peculiar. The perspiratory 

 glands of the axilla and of some other parts also produce secretions differing 

 somewhat from ordinary perspiration. As far as can be ascertained, the cer- 

 umen 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 

 fluidity, but containing a certain quantity of granular and fatty matter. 



The consistence and general appearance of cerumen are quite variable 

 within the limits of health. When first secreted, it is of a yellowish color 

 and 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 semi-solid, 

 dark granulations of an irregularly polyhedric shape, with epithelium from the 

 sebaceous glands, and epidermic scales, both isolated and in layers. Some- 

 times, also, a few crystals of cholesterine are found. 



Chemical examination shows that the cerumen is composed of oily mat- 

 ters fusible at a low temperature, a peculiar organic matter resembling 

 mucine, with sodium salts and a certain quantity of calcium phosphate. 

 The yellow coloring matter is soluble in alcohol ; and the residue after evap- 

 oration of the alcohol is very soluble in water and may be precipitated from 

 its watery solution by neutral lead acetate or tin chloride. This extract has 

 a very bitter taste. 



The cerumen lubricates the external meatus, accumulating in the canal 

 around the hairs. Its peculiar bitter taste is supposed to be useful in prevent- 

 ing the entrance of insects. 



Meibomian Secretion. Very little is known concerning any special prop- 



