688 VERHOEFF AND BELL. 



rays from a 15 ampere carbon arc lamp by means of a quartz lens 

 and quartz prism, and concentrated them upon the anterior focal 

 point of the rabbit's eye by means of a second quartz lens. The diam- 

 eter and focal length of the latter he did not mention. He exposed 

 both normal eyes and eyes from which he had extracted the lenses. 

 The latter were seven in number. The length of the exposures were 

 from one-fourth hour to 6 hours. Following the exposure there was 

 only slight hyperemia of the conjunctiva which disappeared in 24 

 hours. The cornea and lens were unaffected even after the 6 hours'^ 

 exposure. The retina on microscopic examination showed the follow- 

 ing changes: chromatolysis and formation of vacuoles in the cyto- 

 plasm of the ganglion cells. Loss of chromatin in both nuclear layers, 

 the nuclei of the oviter layer becoming homogeneous and their cross 

 striations almost completely obscured. These changes were found 

 just the same immediately after exposure as in the course of the 

 next 12 to 24 hours. After a few days they disappeared and the 

 ganglion cells showed an increased amount of chromatin. In the 

 animal wliich was exposed for 6 hours, however, vacuoles were found 

 in the ganglion cells at the end of 6 days. In the case of normal 

 rabbits' eyes exposed to the same conditions, retinal changes were 

 found only when the eye was removed immediately after exposure 

 and were said to be simply those of light adaptation. 



In the second series of experiments he exposed the rabbits' eyes to 

 a 3 to 4.5 ampere Finsen light. No statement is made as to whether 

 or not a quartz lens or water cell were used, so it is to be presumed they 

 were not. Also no statement is made as to the distance between the 

 eye and the light. Ten eyes altogether were exposed, two being 

 aphakic. The time of exposure was from five to ten minutes. 



In all cases there was marked conjunctivitis, keratitis, and iritis (?), 

 but no changes were ever found in the lens capsular epithelium. In 

 the retina the following changes were foimd in both the normal eye 

 and the aphakic eye, but were more pronounced in the latter: chi*o- 

 matolysis and formation of vacuoles in the cytoplasm of the ganglion 

 cells with changes in the nuclei of the latter. Swelling and begin- 

 ning collapse of the nuclei of the inner nuclear layer. Loss of chro- 

 matism in the outer layer. The vacuolization of the ganglion cells 

 in some cases persisted several weeks.* When a thick glass plate 



* In a footnote Birch-Hirschfeld stated that in one aphakic eye after an 

 especially severe exposure to the iron arc he obtained well marked myelin 

 degeneration of the optic nerve. He also stated that he would later give the 

 details of this experiment, but we are unable to find that he has done so up 

 to the present time. 



