96 



EXPERIMENTAL PHYSIOLOGY 



location of hair on the head. What is its function? Ex- 

 amine one of the hairs on the back of the hand. Cut it. Is 



it sensitive? Pull it. Where is 

 the sensitive portion located ? 

 Where is the seat of growth ? 

 What part of the skin is it most 

 Kke? 



Study the slide showing a ver- 

 tical section of a hair, under the 

 low power of the microscope. 

 Note that the hair is imbedded at 

 the base in a skin follicle, and 

 grows from a skin papilla at the 

 bottom of this folUcle. Note also 

 the sebaceous or oil glands that 

 serve to coat the hair with oil. 



(b) Nails. Make a drawing of 

 your finger nail, showing all areas. 

 What parts are attached to the 

 skin? Why is the part imder the 

 nail called the ^^ quick''? What is 

 one function of the nail? Cut 

 it. Is it sensitive ? Pull it. 

 Where is its sensitive part located? 

 How does it compare with the hair 

 in this respect? Cut a nick in it 

 and examine it from day to day. 

 Does it change position? Where 



tudinal Section: /i, hair shaft, doCS the grOWth of the nail OCCUr? 

 showing its medulla or core; rr\iij n^i c ±' r 



s, sebaceous gland; w, sheath Tabulate all the functions of 

 of skin; /, fatty tissue. (At the hairs, ualls, and skin that you 



base of the hair is seen the 



papilla that forms it.) liaVC leamcd. 



Fig. 46. — Hair-follicle in Longi- 



