REACTION OF SELACHII TO INJECTIONS 131 



gradual at times and the nucleus retains a regular outline, but 

 in other cases the loss of karyoplasm is sudden and the nuclear 

 membrane collapses and is then irregular. Both types of nu- 

 clear degeneration are found in all the specimens examined and 

 both may occur in the same tubule. 



The cellular changes which one observes in nephritis are 

 doubtless due to cellular inanition as well as to poisoning of the 

 cells. Jackson ('16) has described some of these changes in the 

 thyroid of starved rats. Congestion of the organs and injury 

 or destruction of erythrocytes interferes with the general metab- 

 olism of the cells, thus bringing about inanition changes. 



Differences in the process of degeneration in different cells 

 and nuclei in nephritic kidneys may be influenced by their 

 sudden or their slow death. 



3. Liver 



The liver of selachians and probably of other fish is a very 

 important excretory organ, although Fillet ('90) stated that its 

 biliary function is not well developed. Denis ('13) stated that 

 the liver of dogfish apparently has an excretory function, but 

 did not give any reasons for the belief. The liver, like the other 

 organs of selachii contains a large amount of urea (Staedler- 

 Frerichs, '58). v. Schroeder ('90) stated that this amounts to 

 1.36 per cent of the entire liver substance. Heidenhain ('83) 

 found urea in the bile of selachians, Hammersten ('97) stated 

 that it occurs there in large amounts, and Van Slyke-White 

 ('11) detennined the concentration of urea in the bile to be 1.7 

 per cent. This is greater than that in the urine (Baglioni, '06), 

 and more than half as great as that in the blood (2.6 per cent, 

 V. Schroeder, '90). 



All the non-toxic solutions we injected were recovered in the 

 bile. A quantitative determination of the relative amount of an 

 injected solution (pthalein) excreted by the liver showed that 

 there was present in the gall-bladder five and a half hours after 

 injection three times as much pthalein as had been excreted in 

 the urine. Some pthalein had escaped with bile into the intes- 

 tine and some was still present in the bile ducts. In mammals 



