April 30: Weight, 6.8 kilos; the diet consisted of 250 grams rice, 250 grams sugar, 100 grams cracker meal, and 100 grams of meat. On May 3 his weight was 7 kilos. He received 1 gram of caffein by mouth at 12 noon. At 2 p. m. he vomited and tremors were observed. The next day, May 4, tremors were still present though less pronounced. Examination of the urine for sugar and albumin was negative; on May 4, 1 gram caffein was given again and repeated on May 5. On this date his general condition was not good--dog had no appetite and refused to take caffein. As the dog lost 10 per cent of his weight he was put on a meat diet exclusively and the dose of caffein was reduced to 0.5 gram. He became sick after the second dose, and the administration of caffein was therefore discontinued. It was resumed after five days and the caffein was administered in increasing amounts, i. e., on May 18, 0.5 gram; May 19, 0.5; May 20, 1; May 21, 1 gram in two doses of 0.5 each, given at intervals of one hour; May 22, 1 gram. Dog became irritable, but no other symptoms were observed. The administration of caffein was omitted the next day. On the following day when the same dose of caffein was given there was again marked irritability and tremors. The experiment was therefore discontinued. _Dog 22. Male bulldog._ June 24: Dog weighed 13.7 kilos. Diet consisted of meat exclusively; 1 gram caffein was given by mouth; diarrhea developed; no caffein was given for three days. June 28: Dog weighed 13.6 kilos, 1.5 grams caffein given at 10 a. m. June 30: 1.75 grams caffein administered. July 2: Dog weighed 13.5 kilos; 2 grams caffein or 0.15 gram per kilo, caused well-marked thirst, but did not produce any other symptoms. _Dog 20. Female_. May 12: Weight, 7.7 kilos. Fed liberal carbohydrate diet, consisting of rice, 100 grams; sugar 100 grams; meat and cracker meal, a sufficient quantity to flavor the food. May 14: Weight, 7.7 kilos. Examination of urine for albumin and sugar gave negative results. Urine was acid to litmus. May 17: Weight, 7.4 kilos. Three hours after it was fed the dog received 0.5 gram caffein by mouth. The test of the urine the next day for sugar was negative, but a trace of albumin was present. It will be noticed that the doses were increased gradually and that symptoms were observed only after the fourth dose of 0.1 gram per kilo. Later meat was substituted for the carbohydrate diet and the administration of caffein was stopped for four days. At the end of this period 100 mg caffein per kilo was fed daily for five days, and the dose was then very gradually increased. Diarrhea occurred twice, but no other symptoms, the second attack having lasted a few days. The following is a complete record of the experiment: May 19: 0.5 gram caffein 11.45 a. m. May 20: 0.75 gram caffein 12.45 a. m. May 21: 0.75 gram caffein 12 noon; no sugar, no albumin in urine. May 22: 0.75 gram caffein; urine, same condition found; no symptoms.