EFFECTS OF RADIANT ENERGY ON THE EYE. 743 



fixation of nitrogen from the air and lamps specifically designed for 

 abiotic purposes, like the ultra violet lamp of Henri, Helbronner and 

 de Recklinghausen.^^* The last mentioned is a quartz arc of peculiar 

 form taking 1150 watts and giving approximately six times as much 

 abiotic radiation as the lamp used in our experiments. Such a source 

 would therefore give typical photophthalmia in about one minute 

 at 50 cm. and milder symptoms of conjunctivitis and erythema in 

 somewhat less than this time. A comparable degree of activity is 

 indicated for the other sources here referred to. In these cases con- 

 siderable caution must be exercised to avoid even short exposures to 

 the unscreened source, but arcs of this character are highly special 

 in their functions and have no connection with matters of illumination. 



As regards the general effects of the ultra violet portion of the spec- 

 trum, it must be remembered that the abiotic action is chiefly super- 

 ficial and we have shown that even under exposures of great severity 

 there are no indications of any injury to the retina from ultra violet 

 rays even in the aphakic eye. 



In order to make it clear that the results as to abiotic action, which 

 we have obtained from animal experimentation, are substantially 

 applicable to the human eye as well, we may from the standpoint of 

 general theory point out that the effect of the abiotic rays we have 

 shown to be definitely dependent on the quantity of the radiation, 

 the action of which can be reckoned much as if it were a mere mechani- 

 cal force. There is no reason from our experiments or those of others 

 to suppose that such radiations act with much greater intensity on 

 one kind of living cell than on another. We have in addition ample 

 direct evidence that the effect on the human eye and on the rabbit's 

 eye are entirely comparable, for we have shown experimentally that 

 the critical amount of abiotic radiation for photophthalmia on the 

 rabbit's cornea and for erythema on the human skin is the same. 

 As a clinical fact, of which the early observations of Charcot ^^ are 

 typical, in every case of photophthalmia the erythema of the skin 

 surrounding the eye is quite as conspicuous as the conjunctivitis. 

 In fact, wdiile in practically every case of photophthalmia erythema 

 appears, it is very rare in clinical cases to find the stippling of the 

 cornea taken as one of our characteristic symptoms, hence the amount 

 of abiotic energy required to produce photophthalmia, since it will 

 also produce erythema, must be substantially as great for the human 

 eye as for the rabbit's eyes on which most of ovir experiments were 

 performed. 



Our general conclusion, therefore, regarding the effect of radiation 



