iQii] Herman O. Mosenthal 321 



the solid constituents, a lesion of either one of these renal elements 

 might be followed by edema. To establish such a sequence of 

 cause and effect would be very interesting. However, there are 

 many obstacles to be overcome before it may be considered proved. 

 In the first place it is almost impossible in either acute or chronic 

 nephritis to find kidneys which present involvement of only one 

 portion of the renal structure. In the second place no conclusion 

 as to the physiological efficiency of the parts may be obtained by 

 microscopic inspection, nor is it possible, as the clinician knows, to 

 foretell the pathological condition of the kidney from a study of 

 the patient. 



This is the position in which histological pathology has left the 

 question. It must however be realized that even if portions of 

 the kidney appear diseased they may still be able to function nor- 

 mally; and conversely, Symptoms of disease may be accompanied 

 by no apparent histological change. Shlayer, Hedinger and Tak- 

 ayasu have recently emphasized this independence of function and 

 structure. In experimental nephritis it has been found that the 

 uranium and Chromate salts produce kidney lesions which are iden- 

 tical. However, while edema and oliguria occur with the former 

 this is not the case with the latter. Testing out these two forms 

 of nephritis, these authors found that in spite of the similar appear- 

 ance of the kidneys under the microscope, great diversity in the ex- 

 cretory functions exists. That histological pathology has almost 

 yielded its utmost contribution to such problems as that of renal 

 edema is generally appreciated and investigators are turning more 

 and more to experimental pathology and physiology for their 

 Solution. 



Although it is impossible to associate definite kidney lesions with 

 the occurrence of edema, there is a constant relationship between 

 it and renal disease caused by certain poisons. Scarlet fever, preg- 

 nancy, Streptococcus infections often of the tonsil and also else- 

 where, diphtheria and other diseases and conditions frequently give 

 rise to nephritis with edema. Exactly similar lesions of the kidneys 

 occur from other causes but are not accompanied by this Symptom. 

 The same is true of the experimental types of nephritis. It is 

 tempting under such conditions to assume that the edema does not 



