324: SECRETION. 



the entire width of the cartilages. Twenty-five to thirty glands are found in 

 the upper lid, and twenty to twenty-five, in the lower lid. 



Each Meibomian gland consists of a nearly straight excretory duct, -3^ to 

 jfo of an inch (83 to 100 p.) in diameter, communicating laterally with com- 

 pound racemose acini, or collections of follicles, measuring -^ to T |^ of an 

 inch (83 to 200 /*). Fifteen or twenty of these collections of follicles are 

 found on either side of the duct in glands of medium length. Most of the 

 excretory ducts are nearly straight, but some are turned upon themselves 

 near their upper extremity. The general arrangement of these glands is 

 shown in Fig. 101. 



In general structure there is little if any difference between the terminal 

 follicles of the Meibomian glands and the follicles of the ordinary sebaceous 

 glands. They are lined with cells -g-^ to 12 *g 6 of an inch (10 to 20 /*) in 

 diameter. The cells contain fatty globules, but these do not coalesce into 

 large drops, such as are often seen in the ordinary sebaceous cells. The folli- 

 cles and ducts are filled with the whitish, oleaginous matter which consti- 

 tutes the Meibomian secretion, or the sebum palpebrale. 



In addition to the Meibomian secretion, the edges of the palpebral orifice 

 receive a small quantity of secretion from ordinary sebaceous glands of the 

 compound racemose variety (ciliary glands), which are appended in pairs to 

 each of the follicles of the eyelashes, and from the sebaceous glands attached 

 to the small hairs of the caruncula lachrymalis. 



Ordinary Sebaceous Matter. Although it may be inferred, from the 

 great number of sebaceous glands opening upon the cutaneous surface, that 

 the amount of sebaceous matter must be considerable, it has been impossible 

 to collect the normal fluid in quantity sufficient for ultimate analysis. In 

 some parts, as the skin of the nose, where the glands are particularly abun- 

 dant, a certain quantity of oily secretion is sometimes observed, giving to the 

 surface a greasy, glistening aspect. This may be absorbed by paper, giving 

 it the well known appearance produced by oily matters, and it may be col- 

 lected in small quantity upon a glass slide and examined microscopically. It 

 then presents a number of strongly refracting fatty globules, with a few 

 epithelial cells. The cells, however, are not abundant in the fluid as it is 

 discharged upon the general surface ; but if the contents of the ducts and 

 follicles be examined, cells will here be found in great number. Most of the 

 cells, indeed, remain in the glands, and the oily matter only is discharged. 

 The object of this secretion is to lubricate the general cutaneous surface and 

 to give to the hairs that softness which is characteristic of them when in a 

 perfectly healthy condition. 



The chemical constituents of the sebaceous matter are largely fatty. In 

 an analysis made by Lutz, in a case of general hypertrophy of the seba- 

 ceous system, the proportion of water was only 357 parts per 1000. The 

 solid matters consisted of oleine, 270 parts, palmitine, 135 parts, caseous 

 matter, 129 parts, gelatine, 87 parts, a little albumen, butyric acid and so- 

 dium butyrate, with sodium phosphate, sodium chloride, sodium sulphate 

 and traces of calcium phosphate. Cholesterine, which is present so fre- 



