670 VERHOEFF AND BELL. 



interstitial hemorrhages, and shght purulent infiltration of the sub- 

 epithelial tissue. Basophilic and eosinophilic granules were not ob- 

 served in the epithelium, possibly due to the fact that the cells were 

 cast off when this degree of injury was reached. These changes were 

 obtained after exposure to the magnetite arc with and without the 

 single quartz lens. In the experiments with the double lens system 

 the conjunctiva was not exposed. 



The Iris. 



Clinical. Twenty-four to forty-eight hours after an exposure 

 sufficient to injure the lens epithelium, the pupil becomes contracted 

 and the iris shows marked congestion and minute interstitial hem- 

 orrhages in the exposed region. The congestion quickly subsides^ 

 but the hemorrhages may remain visible for several weeks. 



Hi,stoJogicaI. The iris is directly affected only after exposures 

 sufficient to injure the lens epithelium. After exposure to the bare 

 magnetite arc sufficient to produce marked conjunctivitis and kera- 

 titis, but insufficient to produce apparent injury- the lens epithelium or 

 corneal corpuscles, the anterior chamber may contain serum and fibrin, 

 evidently the result of an indirect effect on the iris vessels. After 

 exposures sufficient to injure the lens epithelium, there is seen, in 

 addition to congestion and interstitial hemorrhages, an insignificant 

 exudation of pus cells from the iris vessels. With these changes, few 

 if any individual cells of the iris may show signs of injury. After 

 an exposure of 20 minutes to the magnetite arc and lens system, 

 the albinotic iris in one experiment (Exp. 68) shows marked cell 

 changes similar to those of the lens capsule. The cells affected are 

 the stroma cells, the endothelial cells of the vessels, and the posterior 

 epithelium. From some of the blood vessels the endothelium is com- 

 pletely lost. Tlu'ombosis, however, is not observed. The character- 

 istic basophilic and eosinophilic granules are most noticeable in the 

 cells of the posterior epithelium, no doubt due to the fact that these 

 cells are most abundant. Similar changes are found after 6 days in 

 a lightly pigmented iris (Exp. 56) but here the pigment hides any 

 possible change in the pigment epithelium. In most of the experi- 

 ments with the double lens system the pupil was widely dilated so that 

 the iris was only slightly exposed to the light. 



Posterior synechiae were not observed in any of our experiments. 



