"Modern researches have done much to explain the extent and nature of the protective powers by which the organism endeavors to defend itself against the attacks of all kinds of injurious agencies, and especially against invasion by the germs of infective diseases. It is now a well-established fact that alcohol weakens the normal resisting power of the body against the above-named disease-producing influences. In the hope of contributing something to the explanation of the way in which alcohol weakens the organism, I have made a number of experiments bearing upon the question of the influence of alcohol on immunity. "Early in this century careful experiments went to show that alcohol certainly had some influence upon immunity. Two Americans, Abbott and Bergey, were the first to discover that this agent produces a diminution of the haemolytic complement in the blood-serum of certain animals which were tested. They showed also that the formation of specific haemolytic receptors (immune bodies) may be retarded by the action of alcohol. "The extent of the evil effects upon the human body resulting from the consumption of alcoholic liquors is as yet far from being fully known, and stands in need of scientific verification. Many other injurious influences such as unsanitary dwellings, bad feeding, excessive toil, and toxic agents like nicotine, etc., may produce somewhat similar morbid effects. It is therefore necessary, in the scientific study of the question, to take these possibilities into consideration. In my investigations, the results of which I am now to lay before you, I have endeavored to select as subjects for my experiments both abstainers from alcohol, and those who indulge more or less in its use, in such a way that their conditions of life and their habits in other respects should be as nearly as possible the same. All persons, for instance, suffering from any acute or chronic disease were rejected, and very few of the persons selected were smokers. The subject of this research has been human blood, and especially its two principal components, namely, red blood-corpuscles and blood-serum, both of which up to the present time have been very little studied in relation to the question under discussion. I have gone into these matters chiefly because the modern theoretical study of immunity during the last few years has, in general, attracted greater attention to the blood, and shown the important role which the different parts, properties, and capacities of the blood play in defending the organism against internal and external injurious agencies. Further, the subtle methods employed in the study of immunity (such as organic reactions, and reactions between greatly attenuated organic liquids) would also seem to be available for