14 



THE ELIMINATION OE CAFFEIN. 



Series III. — Experiment A. — Oats diet, 150 mgof caffein per Tcilo injected— Continued. 



Rabbit No. 652. Weight, 1,955 grams. Received 15 cc of 2 per cent caffein sub- 

 cutaneously on June 8, 10.50 a. m. 



None. 

 2.08 



5.33 



Total 7. 41 



June 8. 

 11.05 a. m. 

 12.25 p.m. 



June 9. 



2.00 p.m. 



10.00 p.m. 



Bladder squeezed and urine of the three rabbits composited (2 cc). 

 Urinated 40 cc of light colored urine. 



Bladder squeezed and cage washed. 



Found dead. Autopsy— lungs and liver congested and the blood vessels of the 

 large intestine injected. 



27 hours. 



Rabbit No. 653. Weight, 1,615 grams. Received 2 per cent caffein subcutaneously 



on June 8, 11.05 a. m. 



None. 

 1.86 



4.00 



June 8. 

 11.25 a. m. 

 12.20 p. m. 



June 9. 

 2.00 p.m. 



Bladder squeezed and urine composited (3 cc). 

 Urinated 25 cc. 



Bladder squeezed and cage washed. 



5.86 





Trace. 

 Trace. 



LO.OOp.m. 



June 10. 

 10.00 p.m. 



Bladder squeezed. 



Bladder squeezed and cage washed. 



Total 5. 86 



47 hours. 





Experiment B. — Carrot diet, 150 mg of caffein per kilo injected. 



White rabbit No. 621, weight 1,685 grams, had been used for two similar experi- 

 ments; white rabbit No. 610, weight 1,485 grams, had been used for two similar experi- 

 ments; white rabbit No. 654, weight 2,400 grams, new subject, pregnant. 



No. 621 urinated 15 minutes after injection and 0.125 per cent of the caffein admin- 

 istered was recovered. In the composite urines of the three rabbits, collected 

 forty-two hours after injection, 11.63 per cent of the caffein injected was recovered, 

 while in the urine collected at the end of sixty-six hours 1.65 per cent was recovered, 

 making a total of 13.28 per cent eliminated in sixty-six hours. 



Series IV. 



The elimination of caffein when small doses are given were studied 

 in these experiments. Fifty milligrams per kilo were injected into 

 each of the rabbits of this series. The difference in the amounts 

 recovered in the two groups of rabbits was very striking. Elimination 

 was complete in the rabbits fed on oats, as well as those on a carrot diet, 

 at the end of twenty-four hours. The larger amounts of caffein recov- 

 ered in the latter case maybe due to the greater quantity of urine passed 

 or there may be a compensatory factor in the case of the rabbits 

 fed on oats, retarded elimination in the urine being caused by the 

 increased excretion into the gastrointestinal canal. As will be seen 

 later, the excretion of caffein into the stomach and intestines is greater 

 on an oat diet than on a diet of carrots, but as it is reabsorbed into 

 circulation it ought to be found in the urine ultimately. The elimina- 

 tion of larger amounts of caffein into the gastrointestinal canal is 

 not the cause therefore of the small amounts of it found in the 

 urine when oats were fed. Demethylation is probably increased 

 when smaller doses are administered. 



