The cerebellum of mammals is histologically uniform, but it varies greatly in the relative size of its different parts. The Dutch anatomist Lodewijk Bolk studied a large series of mammalian cerebella, and put forward a general scheme of organization that can be applied to all mammals. Bolk also speculated about the functional role of different regions of the cerebellum, based on the idea that there might be a single somatotopically organized representation of the body surface on the cerebellar cortex. Although his idea of a single map is wrong, Bolk's anatomical descriptions are thorough, and his insights are profound. These descriptions formed the basis for much subsequent thinking about the structure of the cerebellum.