The book contains an evenly distributed mixture of natural history, travel, and observation of human societies, including the towns with their Catholic processions. Only the most remarkable discoveries of animals and plants are described, and theories such as evolution and mimicry are barely mentioned. Bates remarks that finding a new species is only the start; he also describes animal behaviour, sometimes in detail, as for the army ants. He constantly relates the wildlife to the people, explaining how the people hunt, what they eat and what they use as medicines. The book is illustrated with drawings by leading artists including E. W. Robinson, Josiah Wood Whymper, Joseph Wolf and Johann Baptist Zwecker.