It was shown in series A that 0.15 caffein per kilo caused symptoms of
intoxication. Before concluding, however, that this is the smallest
dose which causes symptoms of poisoning, a number of experiments were
performed with smaller doses. It was found that in the great majority
of cases 0.1 caffein per kilo may cause diuresis, but no nervous or
muscular symptoms. In some rabbits, however, even such a dose proved
fatal. Post-mortem examinations in these cases showed the presence
of coccidiosis of the liver, and it will be recalled that similar
observations were made before. It is quite possible, therefore,
that coccidiosis of the liver is an important factor in decreasing
the resistance to caffein. Experiment 551 (p. 25) shows that other
conditions may likewise increase the toxicity of caffein.
_Rabbit 325. White, female. Weight, 1,065 grams. Diet, oats._
March 17: 11 a. m., 6 cc 2 per cent (112 mg per kilo) caffein injected
subcutaneously in the back. About 5 cc of urine squeezed out from
bladder before injecting caffein.
March 17: 1 p. m., hind legs crossed and stretched out, front legs also
extended; rabbit lying stretched out on her belly.
March 17: 5.40 p. m., rabbit still alive, condition somewhat improved.
March 18: 9 a. m., found dead, stiff and cold. _Autopsy_: Hemorrhagic
area at point of inoculation; subcutaneous region of both thighs
presented a hemorrhagic infiltration of the tissues; liver contained
lesions of coccidiosis; other organs apparently normal.
_Rabbit 330. Belgian hare, female. Weight, 935 grams; poorly
nourished._
March 18: 3.35 p. m., 5 cc 2 per cent caffein (107 mg per kilo)
injected into subcutaneous tissues in the back; 5.30 p. m., no symptoms.
March 19: 9 a. m., no symptoms.
March 25: Weight, 825 grams.
_Rabbit 329. Belgian hare, male. Weight, 775 grams; poorly nourished.
Received March 18._
March 18: 3.30 p. m., 4 cc 2 per cent caffein (103 mg per kilo)
injected into subcutaneous tissues in the back; 5.30 p. m., no symptoms.
March 19: 9 a. m., no symptoms.
March 25: Rabbit alive in good condition; weight, 825 grams.
_Rabbit 320. Black, male. Weight, 1,040 grams. Diet, oats._
March 17: 11 a. m., 6 cc 2 per cent caffein (115 mg per kilo) injected
subcutaneously in the back; only a few drops of urine obtained from
bladder before injecting caffein; 1 p. m., rabbit very restless; ran
away when placed on floor; cried when touched with a piece of paper; no
tremors observed, but rabbit became exhausted and was unable to walk;
legs extended out; after running for about a minute dyspnoea was very
marked, but rabbit soon raised himself on his legs; 5.40 p. m., rabbit
up on his legs.
March 18: 9 a. m., found dead, but still warm. _Autopsy_: Lungs studded
with small grayish white nodules, adhesions to costal pleura; probably
lesions of coccidiosis; liver studded with coccidiosis nodules.
Hemorrhages at point of inoculation.
_Rabbit, 551. Gray, female. Weight, January 26, 1,650 grams. Diet,
oats; fed 20 cc of 25 per cent alcohol daily from January 26-31._
January 31: Weight, 1,450 grams; 10.20 a. m., temperature 101.6°;
10.45, a. m., temperature 101.6°; received 7 cc 2 per cent caffein
subcutaneously into back; 11.15 a. m., convulsions of short duration;
raised himself on posterior legs, anterior legs wide apart; 4.10 p. m.,
looked normal, not hypersensitive; 4.30 p. m., condition seemed to be
good.
February 1: 9 a. m., found dead, was alive at 5.30 p. m. of previous
day. _Autopsy_: Lesions found involved thoracic cavity mainly; lungs
were hepatized and a fibro plastic exudate caused them to adhere to
costal pleura; liver engorged and appeared fatty; no marked lesions
affecting digestive tract, a slight catarrh of stomach being the only
noticeable feature; kidneys and spleen normal.