THE SPECIAL SENSES. 53 



How many coats has the eyeball ? 



What is the nature of the outer coafc ? 



What is the cornea ? 



Is the white coat of the eye sensitive ? 



How do you account for the pain felt when a cinder lodges 



on the eye ? 



What is meant by the eye being " bloodshot " ? 

 Does light enter the eye through the white coat ? 

 Through what does it enter ? 

 What is the color of the middle or choroid coat ? 

 What purpose does it serve in the eyeball ? 

 Where and what is the iris ? 

 What gives the eye its color ? 

 What is the pupil ? 



How is the pupil regulated to admit more or less light ? 

 Where and what is the retina ? 



What is formed by the eye on the screen of the retina ? 

 What humor lies between the cornea and iris ? 

 Where and what is the crystalline lens ? 

 What humor occupies the back part of the eye ? 

 Which of these parts is most effective in collecting the light 



on the retina ? 



What is the nerve of hearing called ? 

 By what only is it impressible ? 

 What is the work of the ear ? 

 Into what parts is the ear divided ? 

 What tube leads from the outer ear to the " drum " ? 

 Describe the ear drum. 

 What is the use of the Eustachian tube ? 

 What are the parts of the inner ear ? 

 By what are all sounds produced ? 



Describe the course of sound-waves from a sounding body 

 through the ear to the nerve of hearing. 



What is the organ ot the sense of smell ? 



What is the name of the nerve of smell ? 



To what is this nerve sensitive ? 



Against what does the nerve of smell afford us protection. 



