352 HERMAN O. MOSENTHAL 



extent by the glomeruli" (Rowntree and Geraghty). This statement 

 may satisfy our craving for knowledge in certain directions. It is doubt- 

 ful whether any information regarding the excretion of substances by the 

 tubules or glomeruli at the present moment is of more than theoretical 

 interest to the clinician, because of the very undeveloped state of the 

 physiology and pathology of these structures. Therefore, this aspect of 

 the problem needs no further discussion. 



The other portion of the original question as to what renal excretory 

 products phthalein parallels is of much greater significance. With the 

 development of chemical methods a greater demand has been 'made of 

 renal functional tests than previously ; these methods tell specifically what 

 substances are retained and furnish clear-cut indications in regard to 

 therapy and prognosis. Many attempts have been made to associate 

 phthalein elimination with one or the other of the renal excretory products. 

 The experimental work of Marshall and Kolls possibly comes nearest to 

 a solution of this question. They find that the excretion of sodium 

 chlorid, water and urea, do not follow the phthalein while creatinin does ; 

 furthermore, the very interesting and valuable observation is made that 

 the relative amounts of water and chlorids eliminated depend more upon 

 the blood flow than upon the amount of kidney tissue present, while the 

 importance of the influence of these factors is reversed in the case of 

 creatinin and phthalein. 



From the clinical point of view, it is well established that the retention 

 of creatinin in the blood occurs only when the elimination of phthalein 

 is very much below the normal. The compensatory factors for the excre- 

 tion of creatinin appear to be very great. Therefore, an inference re- 

 garding the retention of creatinin can not be made because the phenol- 

 sulphonephthalein test shows an impairment of renal function. The pos- 

 sibility that the phthalein test parallels the total amount of actively func- 

 tionating kidney substance, irrespective of the volume of blood flow or 

 nervous influence, lends a significance to this test which makes it of much 

 greater clinical importance than formerly. 



For many physicians the phthalein procedure must of necessity remain 

 the method of choice for testing renal function. It requires only a very 

 limited equipment for its performance and no profound knowledge for its 

 interpretation. As medical science develops it will undoubtedly be re- 

 placed by tests which demonstrate the ability to excrete certain substances 

 that have a direct bearing upon the shaping of treatment. Theodore Jane- 

 way (6), in 1913, made a statement, as true to-day as it was at that, time, 

 which gives us the status of the phthalein test as it promises to be regarded 

 almost indefinitely : "The test brought out by Dr. Rowntree is a test which 

 aims at the solution of the old pressing clinical problem, the prognosis, 

 especially as a guide to a surgical procedure. It is admirable and answers 

 that need better than anything else that we possess to-day. From the 



