Rabbit died 30 minutes after last injection of caffein. _Autopsy_: Stomach exhibited marked inflammation of mucosa. Slight enteritis. Liver and kidneys were deeply congested and dark colored. _Rabbit No. 101, white male._ _Diet, oats._ Received caffein subcutaneously as follows: ---------+---------+--------- Date. | Weight. | Caffein | | per | | kilo. ---------+---------+--------- |_Grams._ |_Grams._ Mar. 18 | 2,025 | 0.100 Mar. 19 | 1,970 | .100 Mar. 20 | 2,009 | .100 Mar. 22 | 1,855 | .100 Mar. 23 | 1,738 | .114 Mar. 24 | 1,815 | .166 Mar. 25 | 1,830 | .185 Mar. 26 | 1,710 | .176 Mar. 29 | 1,734 | .219 Apr. 1 | 1,606 | .224 ---------+---------+--------- April 5: Found dead. _Autopsy_: Marked inflammation of gastric mucosa. Considerable enteritis affecting the whole extent of the intestines; liver congested and friable; kidneys deeply congested in cortical and medullary portions; spleen congested, but of normal size; lungs and heart normal. Four days, 0.1 per kilo; 10 doses in 14 days. _Rabbit 201._ _Diet of carrots begun October 1; October 19, oats._ Subcutaneous injections as follows: ---------+---------+--------- Date. | Weight. | Caffein | | per | | kilo. ---------+---------+--------- |_Grams._ |_Grams._ Oct. 9 | 1,000 | 0.150 Oct. 11 | 1,015 | .180 Oct. 13 | 1,065 | .187 Oct. 16 | 1,065 | .225 Oct. 18 | 850 | Oct. 20 | 890 | .111 ---------+---------+--------- Under observation six hours October 20; no symptoms. October 23: Died; was much emaciated but did not show any symptoms; emaciation set in when caffein was withdrawn; urine never contained sugar or albumen; symptoms observed after second dose only. SERIES B.