In the more recent publications dealing with any branch of the wide subject, comprised under the heading of "Peptic Ulcer ", the authors have in many cases prefaced their remarks with an apology for adding to the already over -burdened literature. If, in offering a thesis on "Duodenal Ulcer ", the writer feels that he is exempt from the necessity of making such an apology, it is not because he can claim to have added anything to our knowledge of the subject, but rather from the very opposite reason. In this thesis is to be found little that is new, and perhaps even less that is original. But in a subject so controversial as this, where there is already in the literature a super- abundance of original investigations and original...