THE EYE 389 



2. Why does the body not need a light-producing apparatus, corre- 

 sponding to the larynx in the production of sound? 



3. How is the light from a candle made to form an image? 



4. What different things must happen in order that one may see an 

 object ? 



5. Make a sectional drawing of the eyeball, locating and naming all 

 the parts. 



6. Of what parts are the outer, middle, and inner coats of the eye- 

 ball made up? 



7. What portions of the eyeball reflect light? What absorb light? 

 What transmit light? What refract light? 



8. Show how the iris, the crystalline lens, the retina, the ciliary 

 muscle, and the cornea aid in seeing. 



9. Trace a wave of light from a visible object to the retina. 



10. Why does not the inverted image on the retina cause us to see 

 objects upside down ? 



1 1 . What change occurs in the shape of the crystalline lens when 

 we look from distant to near objects ? From near to distant objects ? 

 Why are these changes necessary? How are they brought about? 



12. How does the method of adjustment, or accommodation, of the 

 eyeball differ from that of a telescope or a photographer's camera? 



13. With two eyes how are we kept from seeing double? 



14. What different purposes are served by the tears. Trace them 

 from the lachrymalglands to the nostrils. 



1 5 . Show how the proper lenses remedy short- and long-sightedness. 



16. Describe the conjunctiva and give its functions. Why should 

 it be so sensitive ? 



17. How may eye strain cause disease in parts of the body remote 

 from the eyes? 



18. How does "image stimulation" differ from light stimulation in 

 general? 



PRACTICAL WORK 



To illustrate Simple Properties of Light. i . Heat an iron or 

 platinum wire in a clear gas flame. Observe that when a high 

 temperature is reached it gives out light or becomes luminous. 



2. Cover one hand with a white and the other with a black piece 

 of cloth, and hold both for a short time in the direct rays of the sun. 

 Note and account for the difference in temperature which is felt. 



