It is common knowledge that a person addicted to the use of morphin may gradually increase the dose of the drug without suffering toxic effects, so that in a few months he may take with impunity a dose that originally would have been fatal. In other words, he establishes an immunity to the drug; and it seems probable that the immunity is due to the presence of an antibody or antitoxin in the blood.
When later the morphin is withdrawn, the antibody remains in the blood unneutralized, and according to the theory that is generally accepted, it is this antibody that gives rise to the characteristic symptoms of nervousness, leg pains, sweating, nausea, vomiting, diarrhea, etc. These symptoms are relieved when morphin is administered, and the amount required to give relief is precisely the dose to which the morphinist has habituated himself. A less amount relieves the symptoms only in