12 



THE ELIMINATION OF CAFFEIN. 



SERIES I. Three rabbits (Nos. 607, 608, and 619), each receiving 150 mg of caffein per 



kilo subcutaneously . 



Series II. 



The object of this series was to ascertain when the elimination of 

 iin began and the length of time during which it continued. The 

 urines at the end of the first hour as well as at the end of 49 hours 

 were examined for caffein. In the oat-fed rabbits 36 mg, or 4.8 per cent, 

 were eliminated during the first hour. In the parallel experiment, in 

 which carrots were fed, only 2 per cent of the caffein administered 

 was found in the urine at the end of the first hour. The urine of the 

 next 24 hours contained 7.18 and 9.23 per cent in the case of the 

 rabbits on oats and on carrots, respectively. At the end of 49 hours 

 the amounts of caffein recovered were 1.94 per cent in the experiment 

 with oats and 1.29 per cent in that on carrots. 



The total amounts of caffein recovered in the entire period showed 

 that the rabbits which were fed oats eliminated about 1.5 per cent 

 more than those fed on carrots. The loss of some of the urine in the 

 latter case makes it probable that the difference was smaller than 1.5 

 per cent. The results of this series indicate, therefore, that the 

 amounts of caffein which are eliminated unchanged may be inde- 

 pendent of the diets employed in these experiments. 



SERIES II. Three rabbits (No. 619 of Series I being used again); eacn received 150 mg 



per kilo subcutaneously. 



