THE SPECIAL SENSES 343 



see anything. In the following experiment shut the right 

 eye, and be careful not to let the eye waver: 



* Read this line slowly. Can you see the star all the time ? 



If not, change the distance to the book and read the line 

 again. In the human eye the optic nerve enters not in the 

 center, but at a point toward the other eye. Although the 

 optic nerve along its course is not sensible to light, yet if it 

 be cut, it does not give pain, but gives the sensation of a 

 flash of light. 



621, THOUGHT LESSON. The Eye. (In writing out 

 this lesson, underline the words you supply.) 



1. The eye is shielded from blows by bony projections of 

 , , and . 



2. The hairs of the eyebrows lie inclined toward in 



order to turn from the . 



3. The eyelashes are to keep out and . I find 



by trying it that I [can or cannot] see the position of a 

 window with my eyes closed. 



4. The tears are to . We wink in order to carry 



the over the , also in order to and to . 



5. The front of the eyeball looked at from the side is 



seen to be . It is called the cornea. The colored 



portion of the eye, the iris, is to the amount of . 



6. The hole in the iris, occupied by the transparent 



aqueous humor is called the . It is for the purpose 



of . 



7. It appears to be black because no is from 



the interior wall of the eye. I know that the iris is 

 partly muscle, because it the size of the . 



8. By holding my finger in line with writing on the black- 

 board, I find that I [can or cannot] see both finger and 

 writing distinctly at one time. This is because in order to 



focus the upon the , the must change shape 



for every change in the distance of the object looked at. 



