André Rançon, who embarks on a scientific expedition to the Haute-Gambie under the direction of the French colonial administration. Rançon discusses his preparations and the circumstances leading up to his journey, including the formation of his caravan consisting of local guides and laborers. He describes the initial stages of his journey, dealing with health challenges, a lack of supplies, and the hospitality of the local chief, Sandia-Diamé, as he seeks to navigate and document the rich biodiversity and cultural landscapes of the region. Rançon's detailed observations of the villages, inhabitants, and the natural environment form the foundation of his scientific inquiry and set the stage for the subsequent chapters of his expedition. (This is an automatically generated summary.)