The clinical diagnosis of pinealoma.

In spite of concerted efforts by many investigators, the function of the pineal gland remains an enigma. Certainly un­ derstanding has progressed since the ob­ servations of the philosopher Herophilus who thought that the pineal was a sphinc­ ter to control the flow of thought from the ventricles or Descartes’ proclamation that the pineal was the “ Seat of the Soul.” U n­ fortunately, no investigator has yet iden­ tified a single hormone produced exclu­ sively by the pineal gland that influences a distanttargetorgan(s). Therefore, a review of pineal physiology is a prerequisite to understanding the difficulties encoun­ tered in the diagnosis of pineal gland tumors.