HELMHOLTZ IN KONIGSBERG 



the side of a living eye, three reflections, or little 

 specks of light, may be seen in the eye. The brightest 

 one, an erect image, is on the anterior surface of the 

 cornea ; the next, also erect, but much less distinct, 

 is on the anterior surface of the crystalline lens ; and 

 the third, extremely faint and difficult to see, is 

 inverted and comes on the posterior surface of the 

 lens. The one on the anterior surface of the cornea 

 has no doubt been long familiar, the ' light of the eye,' 

 represented by artists in a portrait by the little speck 

 of yellowish white paint. The next, on the anterior 

 surface of the lens, was long ago observed by Sanson, 

 who looked for it in connection with the appearance of 

 cataract ; while the third was first discovered by one of 

 the older physiologists Purkinje, who detected many 

 things, so that his name appears in every physiological 

 text-book. A Dutch observer, Cramer, made the 

 happy observation that if the eye suddenly transfers 

 its gaze from a distant to a near object, the middle 

 image moves nearer the most anterior image, and at 

 the same time becomes smaller. As this image is a 

 reflection from the anterior surface of the lens, and 

 as an image on a more convex lens is always smaller 

 than one on a less convex surface, it will be evident 

 that when the eye focusses on the retina the more 

 divergent rays that come from a near object, it 

 changes its curvature and becomes more convex. 

 Accommodation, then, consists in an increasing 

 convexity of the lens, beginning when the eye looks 

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