-------+--------+---------+-----------------------+------------------- Number.|Weight. | Caffein | Symptoms. | Duration of life. | |per kilo.| | -------+--------+---------+-----------------------+------------------- |_Grams._| _Gram._ | | 91 | 3,050 | 0.15 | 1 hour 40 minutes | 2 hours. 88 | 3,260 | .15 | | 1 hour 40 minutes. 92 | 1,750 | .16 | 25 minutes | Survived. 87 | 2,620 | .15 | 3 hours | Do. 90 | 2,685 | .20 | 1 hour 15 minutes | Less than 18 hours. 89 | 2,860 | .20 | | 75 minutes. 82 | 2,450 | .15 | | Less than 24 hours. 100 | 2,740 | .124 | 1 hour 40 minutes | Survived. 93 | 1,640 | .125 | | Do. -------+--------+---------+-----------------------+------------------- SUMMARY. The toxicity of caffein in cats is shown to be the same when given by mouth as when injected subcutaneously, the minimum fatal doses in both cases being 0.15 gram per kilo. When introduced by the intraperitoneal route, caffein is, on the contrary, distinctly less toxic. After the administration of 0.137 and 0.145 gram caffein per kilo (Nos. 93 and 87) salivation in one cat (No. 93) and irritability and muscular stiffness in the other were the only effects noticed. These symptoms were no longer observed the next day and the cats appeared to be perfectly normal. Experiments with larger doses indicate that the minimum fatal dose by this method of administration is about 0.2 gram per kilo. EXPERIMENTS ON DOGS. The experiments were carried out on well-fed adult dogs and on puppies, kept under observation for some time before the drug was administered. Only those manifesting no signs of abnormality were used for these tests. Caffein was given by mouth mixed with 10 to 20 grams of meat, or subcutaneously in 2 per cent aqueous solution. The young animals received caffein dissolved in milk. The determination of the minimum toxic or fatal doses when the drug was fed presented considerable difficulty, as in many instances the ingestion of the drug was closely followed by vomiting. ADMINISTRATION BY MOUTH. SERIES A.