220 LABORATORY GUIDE IN PHYSIOLOGY. 



on opposite sides of the table. Let the subject close or 

 screen one eye. 



(1) Hold any object directly in front of the subject; let 

 the subject keep his gaze continually fixed upon the 

 object. Move the object quickly toward the subject's 

 left, and note the fixation anew of the object in its new 

 position. What muscle or muscles accomplished this 

 act of monocular fixation? 



(2) Move the object quickly in the opposite direction, 

 then upward, downward and diagonally, noting the 

 instantaneous adaption of the eye to the new 

 direction, recording also the muscle or muscles involved 

 in each act. Are all the movements apparently equally 

 ready and exact ? 



(3) Bringing the object to a point directly in front, 1 m. 

 distant, note through how great a lateral movement it 

 may be carried without inducing any discernible change 

 in the visual axis of the eye. 



(4) Bring the object to the central position and move it 

 very slowly outward in any direction, noting whether 

 the changes in the direction of the visual axis are 

 equally slow and regular. 



2. Binocular fixation, convergence. 



In the above experiments it was probably noted by both 

 subject and observer that the closed or screened eye 

 responded to every movement of the other eye. 



(5) With both eyes open and fixed upon an object held 

 directly in front at a distance of about 1 m., let the 

 observer move the object quickly, then slowly, right, 

 left, up, down, and around, and observe the continuous 

 perfect fixation of the object with both eyes. 



(0) "What muscles are involved in following an object 

 from one's right side to his left ? In each other di- 

 rection in turn? 



