120 PHYSIOLOGY FOR THE LABORATORY. 



b. The eye of a cat. 



Study the eyes of a cat during sudden changes in the 

 amount of light. 



G. Binocular Vision. 



While holding a pencil about a foot in front of the 

 eyes, look at a distant object. How does the pencil 

 appear? Close the' right eye. What change is there? 

 Close the left eye and open the right. 



H. The Blind Spot. 

 Marriott's experiment : 



With the following figure find the blind spot in your 

 own eye. Close the right eye and hold the figure about 

 ten inches in front of the left eye. Look steadily at the 



FIG. 12. 



cross with the left eye and gradually draw the page 

 toward the eye. Do you find a place where the circle 

 disappears? The image then falls on the entrance of the 

 optic nerve, or the blind spot. 



I. The Yellow Spot. 



Clark-Maxwell's experiment: 



Material. Chrome alurn, a strong solution. 

 Apparatus. A glass bottle with flat sides. 



