My own present opinion and conception remains as expressed in a paper, “Narcotic Addiction--A Systemic Disease Condition,” written in 1912 and published in the _Journal of the American Medical Association_, Feb. 8, 1913, as follows, “It is my opinion that, however much increased oxidation aids in the handling of morphine, it is to the formation of an antitoxic substance that we must look for explanation of our clinical manifestations and for the classification of morphine-addiction as a definite medical entity. This opinion is based on certain clinical manifestations of morphine effect and the symptomatology attending insufficient supply of morphine to those addicted, on certain phenomena observed during and following treatment, on the persistence of tolerance and on the susceptibility of the cured patient to the re-formation of addiction.” Before elaborating this conception of addiction-disease, I think it desirable to repeat the enumeration of the principal manifestations of “withdrawal” or body-need for opiate drug. In a general way, they may be said to begin with a vague uneasiness and restlessness and sense of depression and weakness; followed by yawning, sneezing, sweating, excessive mucous secretion, nausea, uncontrollable vomiting and purging or diarrhea, twitching and jerking, sometimes violent jactitation, intense muscular cramps and pains (described as if the flesh were being torn from the bones), abdominal pain and distress, marked cardiac and circulatory insufficiency, and irregularity (often with marked dyspnea), pulse going from extremes of slowness to extremes of rapidity, with lowered blood-pressure and loss of tone, facies drawn and haggard, pallor deepening to greyness, exhaustion, collapse and in some cases, death. _Essential Mechanism of Narcotic Drug Addiction-Disease_ If such clean-cut, strikingly apparent, constant, and undeniably physical phenomena and symptomatology as I have described are to be adequately explained, there must be some physical mechanism, some definite body process working upon fundamental principles of disease reaction. They certainly are not psychiatric manifestations nor the expressions of habit, appetite, vice, nor morbid indulgence. Enjoyment of morphine for itself, even in such patients as have ever experienced such enjoyment, is lost long before the stage of rooted or completely developed addiction is reached. Physical results must be explained by physical cause.