778 HENRY G. BARBOUR 



activity and to ascribe its origin to more than a single antecedent. The 

 ammonia output appeared to bear little relation to the lactic acid elimina- 

 tion. 



Purins. The chief therapeutic value of the purin bases lies in their 

 diuretic property which quite possibly plays the chief role in all of their 

 effects upon the metabolism. 



Water Metabolism. In purin diuresis the water of the urine is in- 

 creased proportionately more than the solids, which also show an absolute 

 increase. The extent of water excretion depends much upon the supply. 

 Widmer(a), for example, has shown that caffein diuresis is abundant in 

 dropsical conditions, but fails altogether with dry feeding. On the other 

 hand, during the diuresis of diabetes mellitus E. Meyer has shown that 

 caffein produces no further effect. The reputed superiority of theobromin 

 and theocin as compared with caffein Sollmann ascribes to the fact that 

 the last mentioned is possessed of more toxic side actions which prohibit 

 its being administered in such large amounts. 



Schroeder(fc) observed that the water content of rabbit's blood is de- 

 creased by ten per cent after an effective caffein diuresis. Spiro states 

 that theocin also lessens the absolute amount of water in the blood besides 

 the percentage concentration of sodium chlorid. 



The secretory theory of caffein diuresis was advanced by Schroeder. 

 It received strong support from the experiments of Richards and Plant, 

 in which it was shown that when the in vitro perfusion flow is kept con- 

 stant caffein increases the artificial urine. On the other hand, there is 

 a mass of evidence which relates puriii diuresis to an increased circula- 

 tion through the kidneys. For a full discussion of the mechanism the 

 reader is referred to Cuslmy's monograph. 



Nephritic Conditions. Pearce, Hill and Eisenbrey and others have 

 shown that the diuresis fails to occur in experimental glomenilar nephritis. 

 Christian has found theocin of little diuretic value in nephritis except 

 in cardiorenal cases with edema. Here he finds that it increases the 

 sodium chlorid excretion and works best when given with digitalis or 

 intermittently. 



MacXider finds purin and other diuretics ineffective in anurias pro- 

 duced by anesthetics except in those cases of ether anuria where the alkali 

 reserve has not been depleted. 



Zondek has recently observed that in cases of high grade hydropic 

 nephritis many diiiretics of the xanthin group cause a decreased flow 

 (with greater concentration) of the urine. This phenomenon, which as 

 yet lacks confirmation, is attributed to "fatigue" of the renal vessels. 



To produce full caffein diuresis in man II. L. Taylor finds that at 

 least 0.5 gram four times a day is necessary. Theobromin-sodium- 

 .salicylate may safely be given in doses twice as large. 



In the human experiments of Means, Aub and DuBois (see below) 



