EFFECTS OF RADIANT ENERGY ON THE EYE. 693 



produced, and by the fact that the epithehal cells of the cornea and 

 lens were unaffected. The screens were such that the lens received 

 waves of the same wave lengths as did the cornea. The corneal 

 epithelium was unaffected probably owing to its being cooled by con- 

 tact with the air. In no instance did the heat reach sufficient inten- 

 sity as to cause pain. 



The most marked heat effect on the cornea was obtained in Exp. 

 88 in which the rays from the magnetite arc after passing through a 

 flint screen and water cell were concentrated for one hour sharply 

 upon the cornea by means of the quartz double lens system. Toward 

 the end of the experiment it was discovered that the water cell had 

 leaked, so that for an unknown length of time the eye had been exposed 

 to infra red rays in addition to the shorter waves. This undoubtedly 

 accounts for the fact that in no other experiment was such a marked 

 heat effect produced, and that no effect was produced in Exp. 85 

 in which the same conditions obtained except that the water cell did 

 not leak and the exposure was longer. 24 hours after the exposure 

 the affected area was hazy and swollen but the eye was free from 

 inflammatory reaction. On microscopic examination 48 hours after 

 the exposure the epithelium was everywhere normal. The stroma 

 was swollen to over twice its normal thickness and stained faintly 

 in eosin. Within the central portion of the exposed area not a 

 single corneal corpuscle could be seen. At the periphery the transi- 

 tion into normal cornea was abrupt as regards the corpuscles but 

 relatively gradual as regards the stroma. In the transition region 

 the corpuscle towards the normal side were in active proliferation, 

 many of them showing mitosis, while from here inward they suddenly 

 became invisible. The endothelium in the exposed region was for 

 the most part completely absent, but in some places a few faintly 

 stained cells still adhered to Descemet's membrane. The cornea was 

 ever^-where practically free from leucocytic infiltration. The iris 

 showed a few minute hemorrhages around the pupil undoubtedly due 

 to heat, since, as stated, the lens capsule was unaffected. (PI. 1, 

 Fig. 3.) 



In the second experiment (Exp. 92) sunlight was focussed 45 

 minutes upon the cornea by means of a large quartz lens after passing 

 through a blue uviol screen and a .001% aqueous solution of auramine 

 O. Here the heat effect was similar but less marked than that just 

 described. The effect on the corneal corpuscles was about as great, 

 and the appearance of the stroma about the same except that it was 

 much less swollen. The corneal epithelium, the iris, and the lens 

 epithelium, were unaffected. 



