CANCEROUS MELANOMA

The skin contains dendritic pigment-bearing cells in the lowermost layer known as chromatophores. They are present in greatest abundance in the dark races. In the Caucasian such cells are rarely evident except in localities protected from light, as in the areola of the nipple and the margins of the anus. The same variety of pigment cell occurs normally in the retina and choroid coat of the eye, in the interstices of the ciliary muscle and in the matrix of hairs. The chromatophore sometimes undergoes cancerous transformation, giving rise to a tumor which is extremely vicious —the so-called melanoma or melanotic sarcoma. As the position of the chromatophore among cells is still undetermined, the place of the melanoma among tumors is likewise debatable. Some regard the chromatophore as epithelial, some as endothelial, others as neurogenic and still others as a connective tissue cell. Consequently, the tumor which it causes is variously