This is the fourth Falk Symposium devoted to the study of intestinal abso~ l 3 tion. As in the case of its predecessors - , I hope that the relaxed atmosphere will enable the participants from all comers of the world to exchange views, not only in this room, but also at less formal moments in the cellar, on the lake, or in the buses that transport us to different parts of the Schwarzwald. We are all eternally grateful to Dr Herbert Falk for undertaking to sponsor this meeting, and to him and his staff for the impeccable organisation which will permit us to work in such a pleasant environment. In the organisation of the programme, one or two innovations have been in­ troduced which are perhaps foreign to routine gastroenterological meetings. First, the average age in this room is rather lower than at most gatherings of this nature, which means that those who carry out the experiments will be responsible for their presentation; they are after all the ones who have made the relevant small observations which lead to the advancement of knowledge.