The following chapters were contributions to Health--a monthly magazine published in New York City. Certain peculiarities of form and considerable repetition of statement--both of which the reader cannot fail to notice--are owing to the fact that about two-thirds of the chapters were written under the caption &quot;Auto-genetic Poisons in the Intestinal Canal and their Auto-infection.&quot; In revising these contributions for book form I have given to each chapter a caption of its leading thought; but I am convinced that repetition of some of the matters treated, especially if the repetition be in a somewhat different connection, is not such a very bad thing. I have used my blue pencil sparingly, and as a consequence the consecutive reader will find that constipation, diarrhea, biliousness, indigestion, auto-infection and proctitis are treated in nearly all the chapters--but with varying applications. Therefore anyone suffering from one of these complaints would better read the whole book instead of only the chapter with the corresponding title.<br /><br />These pages were written for intelligent laymen by a specialist, during a busy, assiduous practice. I take such radical ground, however, going to the very root of the matter, thatthe general practitioner will do well to give my thesis his careful consideration; he should at least glance at the following Introduction for the gist of my claim.