In classifying intracranial tumors we have adopted the suggestion of Cushing that the cases be grouped as follows: (1) tumor of the brain, verified; (2) tumor of the brain, unverified; and (3) tumor of the brain, suspected. In the first group are placed only cases in which the tumor has been seen, either at operation or autopsy, with the exception of gliomatous cysts from which xanthochromic fluid has been obtained by puncture. In the second group are placed cases in which the observations definitely indicate an intracranial tumor, although the tumor has not actually been seen at operation or autopsy. In the third group are placed cases in which the symptoms and observations lead one to suspect a tumor until the lesion is proved something else or until it is verified later as a tumor.
The cases on which this study is based have been taken from the verified group.