Careful observation of this rule in treating trauma to the head will save, many patients who ¡ are now killed by too precipitate operating while they are still in a badly shocked condition. An increase in intracranial pressure, then, is of paramount importance as an indication for operation in injuries involving the brain. From the foregoing we learn that there is a normal intracranial pressure of from 6 to 10 mm. Hg., depending upon the existence of a normal rela-'