200 



BIOLOGY AND HUMAN LIFE 



hair, the follicle, is a cylinder of living cells with a tiny papilla 

 containing blood vessels (see Fig. loo). Connected with the 

 base of the follicle are fine muscle fibers capable of raising the 



hairs, as in the case of the hedgehog's 

 bristles, or in human beings under the in- 

 fluence of a great fright. 



5. Nails. The horny parts of the nails 

 consist of dead cell walls formed in much 

 the same manner as hairs. The living 

 portion at the base of each nail forms 

 successive layers of new cells which are 

 pushed out, new ones taking their place. 



There is usually a layer of fat cells under 

 the skin of well-nourished persons, but fat de- 

 posits may be found in all parts of the body. 

 Like all living tissues of the body, the dermis 

 has blood vessels in it. 



166. Appearances. It may be true that 

 "beauty is only skin deep," but it is quite 

 proper for us to desire good appearance. 

 Indeed, it may be considered a duty to 

 look as well as possible ; for we all like to 

 see nice people, and it is only fair for us 

 to do our share in making the population 

 good to look upon. A clear complexion 

 and good color depend upon proper nu- 

 trition, vigorous circulation, plenty of 

 oxygen, and thorough elimination of 

 wastes. These conditions of the body are 

 to be obtained by correct habits of eat- 

 ing, breathing, exercise in the open, work 

 and play, regular movements of the bowels, etc. If our com- 

 plexion does not please us, we still want it to please others. 

 Many of us think that we have found a short cut to a good ap- 

 pearance by using "skin food" and massage or some other spe- 

 cial treatment which is guaranteed to make us beautiful at least 



Fig. 10 1. Sweat gland 



The sweat gland consistsof 

 a fine tubule opening to the 

 surface of the skin at one 

 end and coiled up in a knot 

 at the other. The coiled 

 portion is surrounded by 

 blood vessels (capillaries) 

 from which water, urea, 

 and salts are withdrawn 

 into the gland tube 



