56 



A COURSE ON ZOOLOGY. 



abundant in certain parts of the face, as on the fore- 

 head and on the sides 



FIG 



of the nose. The oily 

 matter they secrete lu- 

 bricates the skin, pre- 

 serving its softness 

 and elasticity. 



The hair appears in 

 its most advanced de- 

 velopment on the skin 

 covering the cranial 

 bones, but, excepting 

 on the palms of the 

 hand and soles of the 

 feet, a colorless down, 

 having a velvety ap- 

 pearance, may be ob- 

 served over the whole 

 body. The nails are 

 for the anatomist 

 only agglomerated 

 hairs, somewhat 

 changed in form and 

 color. 



The hairs grow 

 from small bulbs or 

 swellings placed in 

 minute cavities in 

 the derm. They are 

 fibrous tubes contain- 

 ing a semifluid matter, 

 and in this is found 

 the coloring principle, 



14 



SECTION OF THE SKIN OP THE SCALP, WITH A 

 HAIR-FOLLICLE (highly magnified) (Leidy). 

 1, cuticle; 2, epidermal rete ; 3, tactile 

 papilla ; 4, dermis ; 5, hair papilla ; 6, ves- 

 sel; 7, hair-bulb; 8, hair; 9, inner root- 

 sheath ; 10, outer root-sheath ; 11, wall of 

 the hair-follicle; 12, erector muscle; 13, 

 sebaceous follicles ; 14, subcutaneous are- 

 olar tissue and fat. 



