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 

 like? 



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 follicle. Note also 

 the sebaceous or oil glands that 

 serve to coat the hair with oil. 



(6) Nails. Make a drawing of 

 your finger nail, showing all areas. 

 What parts are attached to the 

 skin? Why is the part under 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 



FIG. 46. Hair-follicle in Longi- 

 tudinal section: h, hair shaft, does the growth of the nail occur? 



showing its medulla or core; miij. 11 xi f i* f 



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

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



base of the. hair is seen the 



papilla that forms it.) have learned. 



