In an attempt to find a means of relief in cases of hydrocephalus in children, some interesting observations have been recorded relative to the appearance of the functioning ventricle in the living subject. With the object of establishing an outlet through the corpus callosum for the relief of the acute internal hydrocephalus presented in the case reported below, an approach through the dilated ventricle with an operating cystoscope was suggested. An opening through the thinned cortex in a silent area of the brain was planned, as being a far safer procedure than the more formidable midline approach between the hemispheres.1 REPORT OF CASE A baby boy, aged 10 months, Italian, was brought to the neurosurgical clinic, Nov. 5, 1922, by his mother, who requested that something be done to check the progressive growth of the baby's head. The child's birth had been difficult, labor having continued for three days