702 VERHOEFF AND BELL. 



injury the pigment cells have disappeared, and fragmented nuclei 

 can sometimes be seen in the inner layers of the chorioid. The inner 

 layers of the retina, including the ganglion cells, remain normal in 

 appearance. (PI. 4, Fig. 12.) 



In the experiments in which sunlight was used, as already noted, 

 much more intense heat effects are found in the retina and chorioid. 

 Here the inner layers of the retina are disintegrated while the outer 

 layers appear intact. This is undoubtedly due to the fact that the 

 latter have been coagulated and thus fixed by the heat. At the 

 periphery of the area the appearance is reversed, the inner layers 

 being normal while the outer layers show the less marked changes 

 already described. 



Two to six days after such an exposure the coagulated rods and cones 

 maintain their normal appearance except that they stain abnormally 

 deeply in eosin. The nuclei of the external nuclear layer are likewise 

 coagulated, but have lost their cross striations and stain more deeply 

 than normal. The internal nuclear layer shows different appearances 

 in different places evidently according to the heat intensity. In 

 some places the nuclei still take the basic stain and show fragmenta- 

 tion. In others they stain in eosin and are not disintegrated, while in 

 still others they have entirely disappeared. The nerve fibre layer is 

 completely disintegrated and the ganglion cells have entirely disap- 

 peared or stain only in eosin. At the periphery, the ganglion cells 

 with their Xissl bodies stain less and less in thionin as the burned 

 area is approached until they become entirely eosinophilic. The 

 inner surface of the retina is in some cases coated with a thick layer 

 of fibrin. The pigment epithelium is coagulated and retains its 

 normal position in the exposed area. At the periphery it is disin- 

 tegrated. The chorioid behind it shows large extra vastions of blood 

 and marked nuclear fragmentation. There is no cellular infiltration, 

 purulent or otherwise, of either the chorioid or retina. (PI. 4, Fig. 14.) 



After two months the retina is found replaced by neuroglia con- 

 taining migrated pigment cells. In some cases the chorioid is appar- 

 ently normal and the pigment epitheliiun reformed. In others the 

 latter is absent and the chorioid replaced by two or three layers of 

 a vascular fibrous tissue. 



