130 J<»ii:.\AT> OK I 111-; MrrciiKLh Socikty YDec. 



a vasodilation from caffeiii there was an increase in the flow 

 of urine. 



The degree to which the ficnv of nrine is increased is ap- 

 parently not (k^pcndcnt upon the dci^ree of vasodilation (ex- 

 periment (i, table 1) serves cspeeiallv well to illustrate this 

 point. Early in the experiment a vasodilation of -|-82 mm. 

 increased the How of nrine twelve drops per minntes, while 

 later in the experiment a vasodilation of +8] mm. liad no 

 effect in establishing a nrine flow. 



Tn this group of diuretic animals (Group T) a decrease in 

 the flow of urine has resulted from the vasoconstrictor eflect 

 of adrenalin when this action was sufficiently pronounced 

 (tracing 2). 



The degree of vasoconstriction has varied between a mini- 

 mum of — 30 mm. to a maximum of — 76 mm. A decrease 

 in kidney volume of — (58 mm. reduced the flow of urine 

 eight drops per minute, a decrease of — 72 mm. seven drops 

 per minutes, while a vasoconstriction of — 30 mm. failed to 

 affect the flow of urine. The flow remained constant — five 

 drops per minute both before and after the constrictor effect 

 from adrenalin. 



Group HI. Control Experiments 



Morphine-ether anesthesia. The animals of this group 

 were either puppies or full-grown dogs. All of the animals 

 were deeply anesthetized. Following the anesthetic all of 

 the animals remained diuretic. 



The effect of caflein and of adrenalin in this group of 

 animals was very similar to the effect obtained in the pre- 

 viously described group of control animals in which Gre- 

 hant's anesthetic was employed. 



The eflect of caffein was to induce a vasodilation of the 

 renal vessels accompanied l)y an increase in kidney volume 

 varying between the limits of +37 to +87 mm. (tracing 5, 

 table 3). 



Following the vasodilation there was with one exception 

 an increase in the flow of urine. Again in this group of ex- 

 periments it will be seen that the degree of vasodilation is ap- 



