Pigmented moles in various parts of the body not infrequently become the starting-point of melanotic tumors, often of exceedingly great malignancy and widespread metastasis. In 1871 Durante, in Italy, first advanced the view that the cells composing nevi are epithelial in origin and not mesodermal as held by Rokitansky and Virchow, and upon this basis he brought forward a theory of the origin of tumors in a matrix of embryonal cells, a theory which Cohnheim proposed quite independently three years later. More recently Unna, ignorant at the time of Durante's views, strongly advocated the genesis of nevi in epithelium, and since then, especially recently, much has been written on both sides of this question. The followers of Durante and Unna refer to the melanotic tumors arising in moles as melano-carcinomata or as nevo-carcinomata, whereas others continue to speak of them as melano-sarcomata.
Recently, Abesser1 in Orth's laboratory in Göttingen,