Frederick M. Allen 7 



in the subject, interest may now be foctisecl on the octunence ol hypertension 

 with minimal degrees or even absence of kidney lesions according to the cus- 

 tomary examination of routinely stained sections. Any conclusions must be 

 withheld during a study of possible finer changes, such as the Volhard-Fahr 

 pre-sclerosis, particularly Goormaghtigh's afibrillar juxtaglomerular bodies. 



Fig. 1. Example of lesions in dogs with chronic hypertension, produced by 

 intermittent clamping of kidney pedicles (Loesch). 



The Loesch method was not only earlier than that of Goldblaii but may 

 also be held superior to it in many respects as a reproduction of clinical essen- 

 tial hypertension. One of these respects is the absence of the gross atrophy of 

 the kidneys, which in itself sharply distinguishes the Goldblatt conduion 

 from all but rare cases in man. Explantation also furnishes a means of obtani- 

 ing any desired series of biopsy specimens with a minimum of inconvenience 

 or disturbance, and thus of tracing the progress of changes which may be 

 either causative of or secondary to the hypertension. For this purpose an ex- 

 perimental form of hypertension which resembles the clinical essential hyper- 

 tension in the absence of gross renal abnormalities has obvious importance. 



