chap, xxxiv.] THE SKIN. 287 



amorphous mass. The duct itself is a continuation of 

 the outer root- sheath. 



As multiplication goes on in the marginal layer of 

 epithelial cells i.e.. those next the membrana propria 

 the products of this multiplication are gradually 

 shifted forward towards the duct, and through this 

 into the neck and mouth of the hair-follicle, where 

 they constitute the elements of sebum. 



There is a very characteristic misproportion be- 

 tween the size of the hair-follicle and that of the 

 sebaceous gland in the embryo and new-born, the 

 sebaceous gland being there so large that it forms the 

 most conspicuous part, the minute hairs (lanugo) being 

 situated, as it were, in the duct of the sebaceous 

 follicle. 



391. In connection with each hair-follicle, espe- 

 cially where they are of good size as in the scalp 

 there is a bundle, or rather group of bundles, of non- 

 striped muscular tissue ; this is the arrector pili. It is 

 inserted in the hair-sac near the bulbous portion of the 

 hair-follicle, and passes in an oblique direction towards 

 the surface of the corium, grasping, as it were, on its 

 way the sebaceous follicle, and terminating near the 

 papillary layer of the surface of the coriura. The 

 arrector pili forms with the hair-follicle an acute 

 angle this latter being planted into the skin in an 

 oblique direction, as mentioned above and conse- 

 quently, when the arrector contracts, it has the effect 

 of raising the hair follicle and hair (cutis anserina 

 "goose's skin"), and of making the hair assume a 

 more upright position (causes it, as we say, to " stand 

 on end"). At the same time, it compresses the 

 sebaceous follicle, and thus facilitates the discharge of 

 the sebum. 



392. The corium of the scrotum, of the nipple of 

 the breast, of the labia pudendi majora, and of the 

 penis, contains numbers of bundles of non-striped 



