Verocay's1 publication, in 1910, seemed to place the histogenesis of von Recklinghausen's disease on a new basis. He believed that the tumors arose from the cells of the sheath of Schwann. Four years later Herxheimer and Roth2 thought that the connective tissue played a more important part in the origin of the disease than Verocay had ascribed to it, but it was not until recently that sufficient data had accumulated to make it possible to question seriously the interpretations of Verocay and his supporters. Mallory,3 Penfield,4 and Rhoades and van Wagenen5 returned to the older conception, namely, that the tumors arise from connective tissue. On the other hand, Angola and Sabatini6 and Hassin7 published observations that support the conclusions of Verocay. At Barnes Hospital, I had occasion to perform postmortem examinations in two typical cases of von Recklinghausen's disease, in both of which