The nature of these antitoxic substances is not definitely known, but they combine with and destroy the poisons.
In due time the horse is bled, the serum is filtered free of blood corpuscles, and then constitutes the antitoxic serum, which can be standardized to a certain potency.
Immunity against toxins also became a subject of investigation, and the result was the discovery of the antitoxic action of the serum of animals immunized against tetanus toxin by E.
The term " antitoxic " signifies that serum has the power of neutralizing the action of the toxin, as is shown by mixing them together outside the body and then injecting them into an animal.
The antitoxic serum when injected enttinoxic previously to the toxin also confers immunity (passive) against it; when injected after the toxin it has within certain limits a curative action, though in this case its dose requires to be large.