1) Per unit body weight, small Bufo arenarum Hensel compared with large ones, have: a) more diuresis, and b) after the injection of caffeine a larger amount of xanthine derivatives eliminated. In not a single instance was more than 10% of the injected caffeine eliminated in two hours.
2) Toxicity of caffeine is much higher at low temperature (4°C.) and diminishes with thermal increase.
3) At low temperature symptomatology is more intense, diuresis ceases and death comes earlier.
4) Toxicity of caffeine is greater after certain operations and increases in the following order : 1st hepatectomy, 2nd ligature of both ureters, 3rd with both operations together. At 33°C. ligature of ureters considerably increases the toxic action of caffeine.