During the last two decades, much attention has been given by scientists to the metabolite, 5-hydroxytryptamine, otherwise known as serotonin. This metabolite, of wide and varied biological activity, occurs in living organisms, participating in and often affecting many physiological phenomena and inducing some pathological changes hazardous to human health. In the present book, the etiological role which this metabolite plays in carcinoid of the gastrointestinal tract, and in so-called carcinoid syndrome is being reviewed on the basis of voluminous literature accu- mulated during recent...