REACTION OF SELACHII TO INJECTIONS 117 



b. Kidney. 1. The kidney in the first two animals is severely 

 congested. Capillaries are dilated in the glomeruli and among 

 the tubules. Er3^throcytes show signs of degeneration. The 

 glomeruli are not destroyed, but are probably somewhat injured. 

 Many of their nuclei (fig. 6) are either hypochromatic or hyper- 

 chromatic and an occasional vacuole is seen in the capsule. 



Two distinct types of degeneration are seen in the tubules of 

 this specimen and a third type in the second animal. These two 

 types we may call granular and hydropic (vacuolar), and of 

 these, the former greatly predominates. 



The granular degenerative process occurs as follows : I^'irst the 

 cytoplasm loses its network appearance (fig. '7) in which the 

 granules are very small and brightly stained with eosin. The 

 granules become dull and adjacent cell walls disappear and 

 finally the cytoplasm breaks through into the lumen. At the 

 same time the entire tubule may shrink in places and pull away 

 from its connective-tissue capsule. The degenerated mass of 

 cytoplasm may spread and lose all shape (fig. 9). While these 

 processes are occurring the nuclei are degenerating in the follow- 

 ing manner. Most of them shrink, becoming hyperchromatic, 

 and stain poorly. The chromatin may become merely a dull 

 mass (fig. 8). The nuclei may shrink to nearly invisible siz?. 

 In some tubules the nuclei degenerate differently. These grad- 

 ually swell, becoming hypochromatic, and then undergo com- 

 plete karyolysis. Both kinds may be seen in the same tubule. 



The hydropic type of cellular degeneration is that in which 

 vacuoles appear in the cells which gradually undergo cytolysis. 

 The cytoplasm at first undergoes slight granular degeneration. 

 In these cells the nuclei may undergo either hyperchromatosis 

 or karyolysis. There is relatively little hydropic degeneration 

 present in the chromate nephritis and it will be described later. 



Destruction of epithelium is largely confined to the thick- 

 walled secretory tubules of the posterior region of the kidney, 

 where nearly every such tubule shows signs of degeneration. 



There is an increase in the number of leucocy1;es present 

 in the degenerated areas. 



THE JOURNAL OF EXPERIMENTAL ZOOOLGY, VOL. 27, NO. 2 



