16 



THE ELIMINATION OF CAFFEIN. 



., . . - Series VI. 



The rabbits in these experiments were fed caffein by mouth. The 

 feces as well as fche urine were examined for caffein. It will be noticed 

 that the weights of the rabbits employed in these experiments differed 

 but little, all of them being of medium size and of the same age. The 

 amounts of caffein eliminated by the two groups of rabbits differed 

 considerably, as at the end of twenty-four hours a little over 13 per cent 

 of caffein was found in the urine of the rabbits fed on carrots, while 

 those on oats eliminated in the urine during the same time only 8.02 

 per cent. The amounts of caffein recovered from the urine during the 

 next twenty-four hours were 1 per cent for those fed on carrots and 0.9 

 per ceni for those which were given oats. Although the latter con- 

 tinued to eliminate caffein in the urine during the following 24-hour 

 period the amount was rather small. None was found in the urine 

 of the other rabbit during this period. It may be concluded, there- 

 fore, that the elimination of caffein is practically completed within 

 forty-eight hours and does not continue beyond this time. Exami- 

 nation of the feces indicates the presence of appreciable amounts 

 of caffein, which is probably due to excretion into the gastrointes- 

 tinal canal as well as to lack of absorption. It will be noticed that 

 the rabbits which received oats eliminated apparently more caffein in 

 the feces than those whose diet consisted of carrots, which is in all 

 probability due to the difference in the elimination of caffein by the 

 gastric and intestinal epithelium on an oat than on a carrot diet. 



SERIES VI. Rabbits to which 150 mg of caffein per kilo were administered by mouth. 



