The results of these experiments, as observed in five guinea pigs, indicate that two decigrams of caffein per kilo of animal produce symptoms within a half to about two and a quarter hours after injection. Death followed in two guinea pigs 70 minutes to 1 hour after the first manifestations of symptoms. Two others died during the night, while one lived 25 hours after the injection of caffein. Even 2 decigrams caffein per kilo weight might therefore be fatal to the guinea pig. Experiments carried out later have shown, however, that the resistance to caffein is appreciably greater in some guinea pigs. This is indicated by the following experiments, in which doses of 0.2 to 0.24 gram caffein per kilo were administered by the same path.
Series C.
Guinea pig 66. Yellow and dark brown male. Weight, 510 grams. Diet, oats.
October 4: 5 cc 2 per cent caffein (0.2 gram per kilo) injected subcutaneously in the back at 3 p. m.; 5 p. m., no symptoms.
October 5: 9 a. m., alive; condition good.
October 9: Found dead. Autopsy: Congestion of liver, kidney, and small intestine.
Guinea pig 65. White and black male. Weight, 510 grams. Diet, oats.
October 4: 5 cc 2 per cent caffein (0.2 gram per kilo) injected subcutaneously in the back at 3 p. m.; 5 p. m., no symptoms.
October 5: 9 a. m., condition good.
Guinea pig 60. White and gray female. Weight, 320 grams. Diet, oats.