EFFECTS OF RADIANT ENERGY ON THE EYE. 753 



perfectly conclusive since the resulting lesions continued to progress 

 in both eyes alike. In the other experiments the exposures were made 

 immediately after the injections, that is, with the corneas clear, so 

 that the conditions were the most favorable possible for germicidal 

 action of the light. The results in these experiments, moreover, 

 are clear-cut, because if the light had killed the bacteria, abscesses 

 would not have formed. This is proved by Experiment 2, in which 

 in the control eye the bacteria were first killed by exposure to ultra- 

 violet light before they were injected into the cornea. 



Experiments. 



Experiment 1. April 10, 1912, a suspension of virulent tubercle 

 bacilli is injected into each cornea of a rabbit. 



May 1, each cornea shows a small tubercle. The right eye is ex- 

 posed to the quartz mercury -vapor lamp through crown screen 1^ 

 hours at 20 cm. 



May 21, both tubercles have developed as usual. The animal is 

 killed. 



Experiment 2. June 22, 1912, a suspension of Staphylococcus^ 

 aureus in distilled water is injected superficially into the left cornea 

 of a rabbit. The remaining bacterial suspension is then exposed at 

 20 cm. for three minutes to the quartz mercury-vapor lamp. (Cul- 

 ture taken proves that all organisms have been killed.) This suspen- 

 sion of killed staphylococci is then injected into the right cornea of 

 the same rabbit. 



Each cornea is exposed to the quartz mercury-vapor lamp at a dis- 

 tance of 0.5 meter for fifteen minutes. 



June 23, both eyes show marked photophthalmia. The left cornea 

 shows well-marked abscess. The right cornea shows only a faint haze 

 along the tract of the needle. 



June 24, both eyes show increase in photophthalmia, with haze of 

 corneal stroma and central loss of corneal epithelium. The abscess of 

 the left cornea has increased in size and there is now hypopion. The 

 right cornea shows no abscess. Enucleation is performed. 



Experiment 3. Oct. 21, 1913, a suspension of Staphylococcus 

 aureus in distilled water is injected into each cornea of a rabbit, the 

 amount injected into the right cornea being three times that injected 

 into the left. The left eye is then exposed for thirty minutes to the 



