1912.] The Effects of Ultra-Violet Rays upon the Eye. 327 



he showed that following heavy exposures to the Uviol-glass mercury-vapour 

 lamp, which emits rays down to a wave-length of 253 /m/m, degeneration of 

 the capsule cells in the pupillary area occurs, followed two to four days later by 

 regeneration as evidenced by the occurrence of mitoses. Surrounding the 

 damaged area, i.e. at the pupillary margin, a zone of darkly stained nuclei is 

 seen, an appearance which he describes as an epithelial " wall." That this 

 phenomenon cannot adequately explain the condition of the capsular 

 thickening described in Eabbit ISTo. 3 is shown by three points : — 



(a) The epithelial " wall " described by Hess is a narrow ring surrounding 

 a wide circle of damaged cells. The zone of * proliferation described in 

 Eabbit No. 3 is a wide one enclosing a small area of normal or dividing cells. 



(b) The epithelial " wall " appears to be due to a swelling of the cells and a 

 tendency of both nuclei and cell protoplasm to stain more deeply than usual. 

 In Eabbit No. 3 the increased density of staining is present to a slight degree 

 but the proliferation has resulted in a layer two or three cells thick. 



(c) In no other case has cell destruction and regeneration followed an 

 exposure of such slight severity. 



2. It is the first stage of the formation of an anterior capsular cataract. 

 While this was the only animal of the series in which capsular proliferation 

 occurred, it is possible that its absence in the other animals may be ascribed 

 to their falling into one of two classes : — (a) That in which the short exposure 

 was a subminimal stimulus to cell division ; (b) That in which the corneal 

 opacity following heavy exposure acted as a shield to the subjacent lens 

 epithelium. 



It is suggested, therefore, that in this case the light has acted as a stimulus 

 to proliferation of the normal anterior capsule cells, without them going through 

 the preliminary stage of damage, such as occurs after exposures of greater 

 intensity. With this exception, the results of repeated exposure to the 

 Kromayer lamp agree with those of Birch-Hirschfeld (Eef. 8), who exposed 

 dogs at 10 cm. from Uviol mercury- vapour light for 10 minutes weekly for 

 18 months, and found no lenticular opacity or capsule changes. As they 

 developed no corneal opacity they fall into line with the first group of my 

 series. 



III. Preliminary Eeport on the Transmission of Hemolysins to the 

 Aqueous after Exposure to Short Wave-Length Light. 

 Following an exposure to the Kromayer lamp of an intensity such as, in 

 the second series, was repeated frequently over periods of several months, no 

 signs of irritation of the iris or ciliary body are observed by the ordinary 

 methods of physical examination, with the exception of a transient contraction 



