1. The reports of forty-seven cases of actinomycosis, twelve cases of blastomycosis, and one case of sporotrichosis of the vertebral column have been reviewed.

2. The examination of the anatomical and clinical aspects of these cases does not permit them to be visualized in separate groups, and the authors have considered and discussed these sixty cases of mycosis of the vertebral column as a clinical entity.

3. The infection of the vertebrae is most often found to be secondary, with a primary focus of infection situated principally in the respiratory and digestive tracts. The vertebrae are infected either by direct contact with a suppurating focus, in which case the external surfaces of the vertebrae are eroded, or by vascular metastasis, where the bone destruction is found to be central and surrounded by a condensed ring of bone. The first possibility appears to be most frequently the case in actinomycosis; the second, in blastomycosis.

4. The differential diagnosis of mycosis of the vertebrae and Pott's disease, for which the former is usually mistaken, is to be made chiefly on the following grounds:

a. The angular deformity is most often absent in mycosis.

b. Mycosis shows multiple sinuses, more destructive invasion, and a more rapid opening of abscesses than in Pott's disease; the skin lesions in mycosis are characteristic.

c. X-ray examination shows erosion of the cortical portion of the vertebra, erosion which is present on the articular processes and pedicles as well as on the vertebral body, or cavity formation in the cancellous portion, surrounded by a zone of increased density. None of these signs are ordinarily seen in tuberculous spondylitis. The bony rarefaction of the latter disease sometimes gives place to a dense appearance in mycosis.

5. One of the factors in the high mortality rate of mycosis of the vertebral column appears to be the difficulty in making an early clinical diagnosis.