February 19: 12.20 p. m., 5 cc 2 per cent caffein (74 mg per kilo) injected into ear vein in five minutes, edema of the ear, other ear used, 3.5 cc injected in 10 minutes, repeated convulsions; 1.25 p. m., rabbit still alive, frequent attacks of convulsions; 2.30 p. m., found dead. Total amount injected in 15 minutes, 8.5 cc, or 0.126 gram per kilo. It will be observed in the preceding experiments that symptoms of severe intoxication were present in all of the six rabbits, but only two of these (Nos. 294 and 556) died from the effects of caffein. Of those which survived, three received doses of 100 to 114 mg caffein per kilo, and another (No. 292) received 141 mg of caffein per kilo. The death of rabbits Nos. 294 and 556 may be regarded therefore as a case of exceptionally low resistance to caffein. SERIES B. Doses of 160 to 200 mg caffein per kilo were employed in these experiments. The rate of injection was 1 cc per minute, with the exception of Experiment 254, in which 10.8 cc 2 per cent caffein were introduced in 17 minutes and 25 seconds. _Rabbit 562. Gray female. Weight, 1,650 grams. Diet, oats._ February 1: Injection began at 3 p. m., injected 10 cc in 12 minutes; 3.01 p. m. to 3.09 p. m., 3 cc injected, convulsions; 3.09 p. m. to 3.14 p. m., 3 cc injected, followed by violent convulsions, marked opisthotonos; 4.30 p. m., rabbit died; total quantity injected, 16 cc. _Rabbit 561. Gray female. Weight, 1,450 grams. Diet, oats._ February 1: Injection began at 11.40 a. m.; 11.48, rabbit struggled, 7 cc 2 per cent caffein injected; 11.50, convulsions, 10 cc 2 per cent caffein total amount injected; 11.55 a. m., injections stopped; injections resumed 11.58, violent convulsions, injections discontinued, total quantity received, 14.5 cc 2 per cent caffein solution; 1.30 p. m., found dead, did not urinate, 25 cc urine found in the bladder. _Rabbit 560. Gray male. Weight, 1,620 grams. Diet, oats._ February 1: Injection began 11 a. m.; 11.10 a. m., 7 cc 2 per cent caffein injected, rabbit struggled; 1 cc was injected during the next three minutes, rabbit struggled but there were no convulsions, injection stopped; resumed at 11.15 a. m. and continued 10 minutes, 8 cc 2 per cent caffein introduced during this time; total amount caffein injected, 16 cc; reflexes markedly increased; 12 noon, tetanic convulsions off and on until 2 p. m., then remained stretched out on abdomen, extremities extended. February 2: 9 a. m., found dead. _Rabbit 559. Gray female. Weight, 1,875 grams. Diet, oats._ January 31: 4 p. m., convulsions after injection of 9 cc 2 per cent caffein in 14 minutes; 4.08 p. m., convulsions after injection of 7 cc caffein in 8 minutes; 4.10 to 4.12 p. m., injected 2 cc more, rabbit lying stretched out on abdomen, extremities extended; total amount of caffein injected, 18 cc (190 mg per kilo).