These experiments were carried out on well-fed, full-grown gray
rabbits. The diet for several days preceding the experiments consisted
of oats or carrots, which were given ad libitum. The injections were
made into the ear veins from a burette or by means of a syringe, the
temperature of the caffein solution being about 40° C. Attention
was also directed to the effect of the rate of injection and of the
concentration on the toxicity. The minimum toxic as well as lethal
doses were determined as shown in the following experiments.