SCYTONEMA. 



[ 569 ] SEBACEOUS FOLLICLES. 



SCYTONEMA, Berk.— A genus of Oscil- 

 latoriacese (Confervoid Algae), especially di- 

 stinguished by the mode of branching of the 

 filaments. We can only make out with cer- 

 tainty one British species of the genus as 

 now restricted, /S. Myochrous (PI. 4. fig. 19), 

 which grows in alpine bogs and rivulets, and 

 is composed of decumbent filaments inter- 

 woven into a dark brown stratum. 



BiBL. HaYvey, Brit. Alff. led. p. 155; Has- 

 sall, Brit. Fr. Alg. p. 2c55. pi. 68 ; Kiitzing, 

 Spec. Alg. 303, Tab. Phyc. ii. pi. 16 et seq. 



SEBACEOUS FOLLICLES or GLANDS. 

 — These organs exist pretty generally in the 

 skin, and secrete a fatty matter. They are 

 mostly seated close to the hair-follicles, into 

 which their ducts usually open. They vaiy 

 in form, some being simple pouches or de- 

 pressions of the skin, whilst in others the 



Fig. 639. 



Compound sebaceous gland, from the nose, opening 

 upon the surface with a hair-follicle, a, b, c, as in the 

 next figure ; d, lobules of the compound gland j e, hair- 

 follicle (root-sheath) ; /, the hair. 



Magnified 50 diameters. 



deeper part of the pouch is branched, so as 

 to constitute a true racemose gland. The 



naiTower portion, or duct, is variable in dia- 

 meter ; it usually opens into the hau'-follicle. 



Fig. 640. 



Simple sebaceous follicle, from the nose, a, glandular 

 epithelium, continuous with b, the rete mucosuiu ; c, con- 

 tents of the gland, consisting of cells containing fat, with 

 free fatty matter. 



Magnified 50 diameters. 



rather above its middle, but sometimes upon 

 the sm-face of the skin itself. 



Each gland consists of an outer coat of 



Fig. 641. 



Glandular vesicle of a sebaceous gland, a, epithelium 

 continuous with the glandular cells b, containing fat. 



Magnified 250 diameters. 



Fig. 642. 





Cells from the glandular vesicles and the sebaceous 

 secretion, a, small nucleated cell, containing but little 

 fat, and resembling an epithelial cell ; b, cells abounding 

 in fat, without evident nuclei ; c, cell in which the fat- 

 globules are becoming confluent ; d, cell containing a 

 single drop of fat ; e, f, cells from which part of the fat 

 has escaped. 



Magnified 350 diameters. 



