STRUCTURE OF THE SEBACEOUS FOLLICLES. 237 



of various size remain in the sharply defined polygonal cells, 

 corresponding to the position of the fat drops which are 

 enclosed by the rest of the protoplasm. The round vesicular 

 nucleus occupies the centre of the cell. 



In many cases the peripheric gland cells are also filled with 

 fat, whilst in other cases the quantity of fat they contain is 

 very small. The cavity of the sebaceous glands is occupied by 

 an amorphous mass of fatty matter, and the debris of numerous 

 cells. 



The wall of the excretory duct is continuous with the gland 

 sac on the one hand, and with the hair follicle on the other ; so 

 that the gland sac may be regarded as a protrusion of the hair 

 follicle, and this more especially, because the root-sheaths cir- 

 cumscribe the excretory duct of the gland, and are directly 

 continuous with its enchyma cells. 



The wall of the excretory duct consists of a transparent 

 membrane, with an epithelial investment, enclosing a cylindri- 

 cal canal which is for the most part filled with fat. The cells 

 correspond in every particular with those of the external roct- 

 aheath of the hair follicle, and are covered by an epidermal 

 layer that diminishes in thickness towards the gland. 



The number and size of the glands are by no means propor- 

 tionate to the size of the hair. Those connected with the larger 

 hairs consist of several lobules that surround the middle third 

 of the hair follicle like a crescent, and are only separated from 

 it by a small quantity of connective tissue. The size of the 

 glands depends, on the one hand, on the number of lobules, 

 and on the other, on the number of the enchyma cells, and the 

 quantity of fat they contain. 



The excretory ducts of the sebaceous glands, of which there 

 are one or two, open into each hair follicle at an acute angle, 

 so that ultimately the cells are continuous with those of the 

 external root-sheath (Henle). 



The gland lobules of the pubescent hairs are in some parts 

 larger and more numerous than those of other hairs, and their 

 excretory ducts are then also surpassingly large. 



The sebaceous glands are entirely absent in the palm of the 

 hand and sole of the foot, as also on the dorsuin of the third 

 phalanges and on the glans penis. 



