December 21: 9 a. m., stiffness in muscles, but no other symptoms, appetite good, no caffein given. December 22: 11 a. m., received 1.0875 grams caffein, or 0.125 gram per kilo; 3 p. m., depressed in spirits and sick, but no other symptoms observed. December 23: 11.30 a. m., received 1.305 grams caffein, or 0.150 gram caffein per kilo; 1.30 p. m., apparently quite sick, but no other symptoms, had good appetite. December 24: 10 a. m., received 0.175 gram caffein per kilo; 4 p. m., when about to be fed fell over and died; no autopsy. The total amount of caffein given dog 30 was 11.3458 grams, administered for a period of eighteen days. The average daily amount per kilo was therefore 72 mg. The feces became offensive when the amounts of caffein were increased to 75 mg per kilo. It will be observed that in this dog the appetite was uniformly good until the day of his death. Whether or not this is the cause of his resistance to caffein will be discussed later. _Dog 32. White, male, young._ Although he was growing rapidly this dog's weight was constant, but he looked anemic. He received a high protein diet until December 3, when the rations were increased by one-third. This dog was under observation from October 26 to December 6 when the administration of caffein was begun. He then received 50 mg caffein per kilo daily for nine days consecutively without showing any effects, when the dose was increased to 75 mg per kilo, then to 100 mg per kilo. This dose was further increased to 150 mg per kilo without causing symptoms, which was repeated the next day. No symptoms having been observed after such amounts of caffein, 175 mg per kilo were fed. This dose, however, proved fatal within two hours. Record of experiment follows: October 26: Weight, 6.90 kilos. November 3: Weight, 6.90 kilos. November 10: Weight, 6.90 kilos. November 20: Weight, 6.90 kilos. November 29: Weight, 6.55 kilos. December 3: Put into cage, diet increased one-third. December 6, 7, 8, 9: Weight 6.30 kilos; 12.30 p. m., received 16 cc 2 per cent caffein by subcutaneous injection in back, no symptoms of any kind noticed, site of injection normal. December 10, 14: 0.05 gram caffein per kilo. December 15: Received 0.4725 gram caffein by mouth, no symptoms. December 16: Received 0.655 gram caffein, 0.100 gram per kilo. December 17: No caffein given. December 18: Received 0.655 gram caffein daily, 0.100 gram per kilo, no symptoms. December 20: Received 0.8188 gram caffein, 0.125 gram per kilo, no symptoms, appetite good. December 21: Received 0.9825 gram caffein, 0.150 gram per kilo, somewhat uncomfortable, no other symptoms. December 22: Received 0.9825 gram caffein, 0.150 gram per kilo, no symptoms except some uneasiness. December 23: 9 a. m., no symptoms, appetite good; 11.30 a. m., received 1.146 grams caffein, 0.1759 gram per kilo; 1.30 p. m., died while making an effort to get out of cage, tonic contraction of limbs observed before death.