EFFECTS OF RADIANT ENERGY ON THE EYE. 695 



lens epithelium, and heat effects by the haziness of the cornea occurring 

 within 30 minutes after the exposure as well as by the slightness 

 of the conjunctival reaction. Combined effects were also shown by 

 the microscopic examinations, the corneal corpuscles being completely 

 invisible in the posterior layers of the cornea, but present and showing 

 characteristic abiotic effects in the anterior layers. 



The other two experiments were of especial interest because they 

 showed the limit in respect to wave length beyond which we were 

 unable to obtain abiotic effects. The same screen 305 /x^u was used 

 as in Exp. 81 just referred to, in which only heat effects were obtained, 

 but the exposures were longer. In Exp. 82 the exposure was 1| hours 

 and haziness of the cornea was noted within 30 minutes afterwards. 

 The lens epithelium was unaffected, and the only evidence of abiotic 

 action was a slight loss of corneal epithelium occurring after 24 hours. 

 The heat effects on the other hand, were very marked. The corneal 

 endothelium was destroyed in the exposed region and only an occa- 

 sional corpuscle could be seen even in the anterior layers of the stroma, 

 so that any possible abiotic effects on the corneal corpuscles were 

 masked by the heat effects. At the periphery of the exposed area the 

 corpuscles were in active proliferation at the end of 48 hours. In Exp. 

 83 the conditions were the same except that the light was focussed 

 upon the surface of the lens instead of upon the cornea, and that the 

 exposure was interrupted for an hour at the end of the first 30 minutes. 

 Haziness of the cornea was noted within 50 minutes after the first 

 exposure. Following the second exposure there was no loss of corneal 

 epithelium and the only evidence of abiotic action was a slight effect 

 on the lens epithelium. The cells were slightly swollen in a small 

 area and a few of them contained characteristic granules. The heat 

 effect on the cornea was about the same as in the preceding experi- 

 ment. 



According to the foregoing experiments with the double lens system, 

 after an exposure of if hours through a water cell and flint screen 

 (315 /xyu) no changes are produced; after an hour's exposure through a 

 screen (310 /x^t), slight heat changes; through screen (305 mm) marked 

 heat changes; and through still more transparent screens, marked 

 heated changes combined with abiotic effects. With the flint screen 

 (315 nfi) but without a water cell, marked heat changes are produced 

 after 30 minutes exposure, the heat effect of the short waves here 

 being reenforced by infra red waves. It is evident from these results 

 that the specific absorption of the cornea with respect to wave length 

 does not end abruptly, but gradually diminishes from 295 nfx to some- 



