116 PHYSIOLOGY FOR THE LABORATORY. 



s. The blood-vessels of the eye may sometimes be seen 

 in the choroid coat radiating from the blind spot after 

 removing the retina. 



t. Make a diagram of a median vertical longitudinal 

 section, showing the position of the coats, the lens, the 

 chambers, and the humors of the eye. 



u. Label all of the parts that are shown in your sketches. 



B. The Human Eye. 

 Apparatus. A hand-mirror. 

 Study your own eyes with a hand-mirror. 



a. The eyebrows. 



1. Their position. 



2. The direction of the hair. 



3. The thickness and the color of the hair. 



4. The hairless place above the bridge of the nose. 



b. The eyelids. 



1. Their number. Do you see the remnant of 



another lid at the inner corner? 



2. The union of the mucous membrane and the 



skin on the edge of the eyelid. 



3. The openings on the edge of the lower lid. 



(1) How many are there? 



(2) What is their use ? 



4. The larger opening on the slight elevation near 



the inner angle of the lower lid is the open- 

 ing into the nasal duct. 



5. Do you know any animals that have three eye- 



lids ? Do you know any that have no eyelids ? 



