During the latter part of 1920 one of us (L.M.M.) devised a small drill carrying an outer detachable casing, the purpose of which was to trephine long bones in order to secure specimens of living bone marrow for histologic study. The problems which were opened to approach by this new method of study were undertaken jointly in 1921.
To G. Ghedini1 is conceded the credit of marrow puncture for diagnosis and prognosis. In 1910 he elaborated on this method of diagnosis in certain diseases of the blood and presented to the profession a most comprehensive article based on his experience and that of others regarding the importance of his procedure. He concludes some facts of primary importance; namely, that disease of the hematopoietic system can occur without changes in the blood and that there are many variations between bone marrow findings and those of the blood. That furthermore, severe pathology