METHOD OF EXAMINATION. 59 



or small lamp, in a place from which all other light is 

 excluded ; the object being to allow the pupil to dilate as 

 much as possible, so as to expose, to the utmost extent, 

 the interior of the eye. If this is not practicable, light 

 coming from one direction only, such as from a top 

 window or skylight, should be employed. Light reflected 

 from white objects, such as whitewashed walls, a white 

 waistcoat or shirt front, should be carefully excluded ; 

 for it would be apt to cause the production, in the eye, of 

 white images, the appearance of which might interfere 

 with the accuracy of the observer's scrutiny. The plan 

 of examining the sight in the open air, while shielding 

 the eye with the top of a black hat from the reflection 

 of white objects, is far too rough a procedure by which 

 to arrive at correct results. While covering one eye 

 with the hand, and bringing the light close to the other 

 eye, and then drawing it away, we should see if the 

 pupil of the eye which is being examined, contracts and 

 dilates in a natural manner ; that no part of the iris is 

 adherent to the lens ; and that the power of contraction 

 and dilation is the same in both eyes. Each eye should 

 be examined separately ; for one may be completely blind 

 from amaurosis, and yet its pupil will obey the stimulus 

 of light applied to the sound eye, although it will be 

 insensible to that falling on its own retina. While 

 making this experiment, we may see if the corj^ora nigra 

 (the small brownish-black balls that are to be seen. 



