The physiology of horn growth: a study of the morphogenesis, the interaction of tissues, and the evolotionary processes of a Mendelian recessive character by means of transplantation of tissues

Horns of rhinoceros are considered by almost all writers as a structure composed entirely of hair, containing no bony core. In reality the composite hair is similar to the bony sheath of domestic cattle, and a bony excescence is present, but in a very diminished form. Skulls show that the bony protuberance is a prominent growth in some cases, although it usually appears as a rough deposit of bone on the nasal bones. The protuberances are often similar to the rough bony excrescences noticed on the skulls of scurred cattle.