324 



Dr. E. K. Martin. 



[Feb. 5, 



The photographic spectrum to this lamp extends from wave-lengths 590 p/j, 

 to 222 and is most intense between wave-lengths 579 up and 254 fifi. It 

 emits no heat appreciable by means of a thermometer. The current 

 consumption is 2*5 amperes on a 220-volt circuit. 



A. Singh Exposures of High Intensity. 



If the lids are kept apart by a speculum, exposures of one-half to two hours 

 at a distance of 1 inch are followed by the changes in the anterior capsule 

 cells described by Hess (Eef. 10). That is, shortly after the exposure, the 

 cells are swollen and their nuclei show diffuse staining of the chromatin. 

 After 24 hours there is a central area, corresponding to the pupil, in which 

 many of the nuclei are represented by scattered chromatin granules extruded 

 from the still visible nuclear membrane. Surrounding this damaged area is 

 the ring of apparently crowded, deeply stained cells which Hess has described 

 as the epithelial "wall." This "wall" may or may not form a complete 

 circle, and varies in width from about four to eight cells. The appearance 

 is due chiefly to the deeper staining of both nuclei and cell bodies, consequent 

 on the submaximal damage at the pupillary margin, accompanied probably by 

 the heaping up described by Hess. He suggested that the swollen central 

 cells pushed those at the pupillary margin up against the intact ones lying 

 under cover of the iris, and so crowded them closely together. 



Two or three days after the exposure, numerous karyokinetie figures are 

 seen in the damaged area, regeneration taking place in the usual way. 



The inflammatory changes in the anterior part of the eye correspond with 

 those described in detail by Birch-Hirschfeld (Eef. 7) and other writers as 

 following exposure to the Uviol mercury- vapour lamp, etc. There is intense 

 conjunctivitis with sub-epithelial haemorrhages, thickening of conjunctival 

 and corneal epithelium, with subjacent round cell infiltration corresponding 

 to the hyperkeratosis and papillary infiltration seen in the skin after exposure 

 to the Kromaj'er lamp. The pupil is small and the iris h)'peraamic, but I have 

 not observed exudates on iris or ciliary body with the exposures given. 



That these changes are due wholly or almost entirely to rays beyond the 

 visible violet is shown by the absence of all but a slight conjunctival 

 hypersemia following exposures of similar duration, in which a benzol cell 

 is interposed between the lamp and the eye. Benzol is transparent to the 

 rays of the visible spectrum but cuts off all those beyond the violet end. 



An attempt was made to find some substance permeable to rays of 

 the shorter wave-lengths only. P.-nitro-benzene-azo-dimethyl-aniline in 

 N/ 10,000 aqueous solution transmits a band in the red and another beyond 

 the violet, but the intensity of the resulting rays is so low as to produce no 



