12 



Scientific Proceedings. 



are very markedly hyperemic, there is more or less fatty degenera- 

 tion and well marked necrosis and desquamation of the epithelium, 

 later cast formation also occurs. The glomeruli are hyperemic, 

 do not show any distinct histologic lesions. Hemorrhages from 

 them were not observed. The lesions are hardly severe enough to 

 account for the early death of the animals. I have become rather 

 strongly persuaded that the chromates cause death in guinea pigs 

 not primarily by their action upon the kidneys, but in a different 

 way, although nothing definite could be ascertained in this regard. 



Results with Injections of One Half Centigram. — Several guinea 

 pigs died from the first or second dose. Four lived from five 

 months to 15^ months. The immediate reaction from each dose 

 was well marked and it was impossible to give the doses very 

 frequently; the highest was 12 doses in five months. One of these 

 animals receiving five doses in seven months showed merely cystic 

 dilation of some glomeruli similar to that which was observed in 

 controls; 1 in one, apart from well marked epithelial lesions, there 

 was a slight diffuse interstitial process; the other two showed 

 definite small areas of collapse of degenerated tubules but with 

 very little evidence of new formation of connective tissue between 

 them. 



Results with Injections of One Quarter of a Centigram. — Few 

 animals died after the first injections; the immediate reaction on 

 the part of the kidneys in most instances was very slight and the 

 doses could be repeated more frequently. Some of these animals 

 lived for one year or more, one for nearly two years. All showed 

 more or less well marked epithelial lesions with formation of casts, 

 very few interstitial lesions of a character which was not en- 

 Countered in the controls also. In these few there were small 

 areas of collapse of degenerated tubules and very little new formed 

 connective tissue between them. 



Experiments with smaller doses even when very frequently 

 repeated and continued for long periods were entirely negative so 

 far as the kidneys were concerned. 



Hearts and bloodvessels remained normal in all animals. 



The conclusion seems justified that it is impossible to produce 



1 See Ophiils, " Occurrence of spontaneous lesions in kidneys and livers of 

 rabbits and guinea pigs," Proc. Soc. for Exp. Biol, and Medicine, 191 1, viii, 75. 



