In these experiments the rate of injection was about 1 cc of 2 per cent
caffein solution per minute.
_Rabbit 194. White, female. Weight, 1,310 grams._
October 19: Injected 7.5 cc 2 per cent solution caffein (115 mg
per kilo) into the ear vein. Rabbit showed stiffness; paralysis of
extremities appeared soon after.[C] Rabbit survived.
[C] Time of injection inadvertently omitted, but was probably not
slower than in the other cases of this series.
_Rabbit 556. Gray, female. Weight, 1,635 grams._
January 31: 2 p. m., 11 cc 2 per cent caffein (134 mg per kilo)
injected into ear vein, in about 11 minutes; 2.10 p. m., convulsions,
rabbit remained lying on its side; during the rest of the hour it had
convulsions occasionally; 3.20 p. m., convulsions and died. Rabbit did
not urinate after the injection of caffein.
_Rabbit 557. Gray, female. Weight, 1,580 grams._
January 31: 2.30 to 2.37 p. m., 7 cc 2 per cent caffein injected from
the burette at the rate of 1 cc per minute; 2.37 p. m., flow of liquid
ceased, veins were engorged and bled freely, injection was continued
by means of a syringe; 2 cc 2 per cent caffein injected in two
minutes; injections discontinued as convulsions appeared; 2.50 p. m.,
rabbit raised itself but fell over; 3.10 p. m., rabbit assumed normal
attitude, walked about the floor without manifesting any signs of the
effects of caffein; 4.30 p. m., walked about, gait normal, condition
seemed to be good.
February 1: 2 p. m., condition good, appetite good, total amount of
caffein injected, 9 cc 2 per cent solution, or 114 mg per kilo.
_Rabbit 558. Gray, female. Weight, 1,590 grams._
January 31: 3 p. m., given 8 cc 2 per cent caffein in eight minutes;
3.10 p. m., violent convulsions; 3.20 p. m., rabbit was stretched out
on his abdomen, extremities extended, urinated; 4.30 p. m., looked
normal; was able to walk about.
February 1: 2 p. m., condition good, appetite good.
_Rabbit 292. Belgian hare, male. Weight, 1,770 grams._
February 18: 4.26 to 4.39 p. m., 12.5 cc warm caffein solution (0.141
gram per kilo) injected into ear vein, convulsion followed when this
quantity was injected, tonic rigidity of limbs followed soon after;
4.52 p. m., condition unchanged, rabbit on floor, limbs stretched out,
and lying on abdomen.
_Rabbit 294. Belgian hare, female. Weight, 1,350 grams. Carrot diet
for about 10 days before the experiment._
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.