The patient who has swallowed a toxic or lethal dose of laudanum, for instance, usually passes at once into the narcotic state, without any prior excitement.
It is also to be noted that, as in the case of poisons of known constitution, each toxin has a minimum lethal dose which is proportionate to the weight of the animal and which can be ascertained with a fair degree of accuracy.
The unit of antitoxin in Ehrlich's new standard is the amount requisite to antagonize i oo times the minimum lethal dose of a particular toxin to a guinea-pig of 250 grm.
For example, the amount necessary to neutralize five times the lethal dose being determined, twenty times that amount will neutralize a hundred times the lethal dose.
A large lethal dose kills by this action, but the minimum lethal dose by its combined action on the respiration and the heart.