78 E. J. STIEGLITZ 



ized susceptibility to such poisons strongly indicates a difference 

 of function for the different divisions (upper, middle and lower) 

 of the proximal convoluted tubule. For example, Aschoff 

 states that uric acid is mainly secreted by the first and second 

 divisions and that the glycogen in diabetes is chiefly stored and 

 secreted by the last portion. It is on the basis of such remark- 

 able localization of damage that the studies of this series were 

 made, for with the tubules functionally destroj^ed, any alteration 

 in secretion would indicate the route through the kidney of the 

 substance excreted. 



Of all the nephritis substances uranium is the most interesting. 

 Not only is it the only poison with which chronic nephritis has 

 been produced, but it is the only one which causes edema. The 

 latter characteristic was first demonstrated by Richter (84, 85) 

 and has been since confirmed by numerous investigators. The 

 first microscopic evidence of uranium nephritis was recorded by 

 Leconte in 1854 and the earliest careful observations reported 

 by Chittenden and Lambert in 1889. Richter showed that 

 there was more edema when salt and water were given than when 

 water was given alone, and believed the chloride retention the 

 essential feature of the edema. However, Georgapulos (86) 

 found more water than chlorides retained while Schirokauer (87) 

 reported a rise in the sodium chloride concentration of the 

 tissue. Whether or no the salt retention is primary is still in 

 doubt. Schneider (36), working with Petromyzon fluviatilis, 

 was able to trace the source of the uranium through the cells of 

 the convoluted tubules by precipitating a brown salt with potas- 

 sium ferrocyanide, picric acid, and hydrochloric acid. Further- 

 more, in many of his specimens he found ferric iron, and reported 

 similar pictures to those we have described under series I. In 

 connection with uranium nephritis from the functional and 

 regenerative points of view, the work of Oliver (27, 88) is of 

 great value. 



In the series of pathologic studies the experiments may be 

 arranged into five groups — those dealing with the effects of 

 uranium, tartrates, chromates, mercuric bichloride, and finally 

 diphtheria toxin. These groups will be described separately. 



