THE SKIN AND BODILY TEMPERATURE. 91 



C. The Microscopical Structure of the Skin. 



Material. A microscopical slide showing a cross-section of the 

 skin of the head. 



Apparatus. A compound microscope. 



With the compound microscope examine a prepared 

 slide showing a cross-section of the skin of the head, and 

 find as many as possible of the following parts. 



Notice : 



a. The epidermis. 



1. Its thickness. 



2. The three layers of cells. 



(1) The outer layer of elongated horny cells. 



In which direction are they elongated ? 

 Have they any nuclei ? What is their 

 relation to dandruff? 



(2) The second layer of rounded cells. 



(3) The third layer of columnar cells. In which 



direction are these cells elongated? 

 Have they any nuclei ? Compare 

 with the outer layer and determine 

 the relative amount of life in the 

 two layers. Inferences. 



b. The dermis. 



1. Its thickness. 



2. Its structure. 



3. The hair. 



(1) The root of the hair is the part embedded 

 in the skin. 



