352 W. LeConte Stevens—Physiological Opties. 
Y Y ‘L 
and not otherwise discoverable except by temporarily paral- 
yzing the ciliary muscle. 
4, Revation oF PupmtaAry AREA To AxtAL ADJUSTMENT. 
Pupillary change usually accompanies change of aceommoda- 
tion, though not an exact index of it. During the recent ex- 
periments measurements were made of the diameter of the pupil, 
of fig. 4, that for the near-point, when a = —5°, the pupil is 
larger than for the far-point whe ° 30’. If a exceed 
45° there is no perceptible variation of the pupil when far- 
point and near-point are successively regarded. 
> 
= 
& 
I 
a 
Pupillary areas, in square millimeters. 
—5° +3° 30’ 5 
Optic angle, -.-..-.. 5° = + 60° 
Maximum area, -.--. 12°4 70 3°0 } tap’ 
Minimum area, - - - - -- 8°2 4:2 Pat 12 
rower 
that the observer’s eye is perfectly free from such cefects as 
consciously, by every one who uses a stereoscope that is ill 
adapted to his eyes and stereographs that are improperly 
mounted. 
