The indispensability of roentgen-ray examinations in general medicine is well recognized. Few physicians realize, however, how much assistance the roentgen-ray picture of the skull and of the spine can afford the neurologist and the psychiatrist. Certain cases of congenital brain syphilis, of traumatic epilepsy, of pituitary disease, of cerebral arteriosclerosis, of cervical rib and of a few other conditions have, in our experience, been diagnosticated chiefly on the basis of the roentgen-ray findings.
Nothing is more disappointing, on the other hand, than the roentgen-ray findings in brain tumor. There are few cases of brain tumor in which the roentgen ray gives us any information other than that which we already possess from clinical findings. It is usually of no help in localization.
All of this is, perhaps, on the point of being radically changed by the principle of photographing the ventricles of the brain filled with air. This idea was