104 Physiology of the Kidney 



ture of most of the suggestions which have been made in re- 

 gard to etiology, it is unnecessary to magnify them. It is 

 definitely demonstrated that hypertensive disease can be pro- 

 duced by renal ischemia in animals where the biotic complex 

 does not contain repression psychoses, psychic trauma or ge- 

 netic predisposition; there is good evidence that disturbed 

 renal function is in some instances the cause of hypertension 

 in man ; and our present evidence shows that in all hyperten- 

 sive subjects so far examined renal function is disturbed in 

 some degree, sometimes only slightly and sometimes mark- 

 edly, but always in the qualitative direction to be anticipated 

 if renal ischemia is in any way important. Whether this renal 

 ischemia is cause or effect and, if it is a cause, how the ischemia 

 itself is initiated, are questions that remain for further ex- 

 amination. 



When and if it can be demonstrated that the relief of 

 renal ischemia specifically abolishes all signs of hypertensive 

 disease in man, then the major link in the chain of logic which 

 incriminates the kidneys will be complete. This is asking that 

 we reach our desideratio sumnta, the cure or prevention of 

 the disease, at the beginning of our problem, which is per- 

 haps more than we can expect, but short of this demonstra- 

 tion it is impossible to charge the kidneys with sole responsi- 

 bility. 



Since, however, the evidence pointing to the importance 

 of renal ischemia is so strong, it would seem the course of 

 wisdom to start from this point and, joining forces with the 

 surgeon, the neurologist and the psychoanalyst, to work 

 backwards, as it were, through the maze of environmental, 

 psychological and hereditary factors in our efforts to discover 

 such other causes as may be operative, and to relate the renal 

 ischemia to the organism as a whole. 



