One mechanical circumstance involved in the pituitary personalities may be the determinant of the entire life history.  That is the emphasized fact that the pituitary is encased in a small bony box, at the base of the skull.  The size of this bony box, and its capacity to yield to the various pressures of a pituitary enlarging to meet the demands of the organism, will often spell happiness or misery, success or failure, genius or idiocy for the man or woman.  Certain possibilities are conceivable.  All of them occur, for the developments of X-ray technique have rendered available almost a direct view of the sella turcica.

In the first place, the bony box may be definitely too small to start in with.  That means a small and so potentially inadequate pituitary, both anterior and posterior, potentially inadequate in that it will become impossible for it to grow and produce extra secretion upon demand.  Handicapped thus, the unfortunate so born is doomed to inferiority and very little can be done for him.  He will not develop satisfactorily.  He possesses small genital organs which will not evolve properly in adolescence, or if they will not stand still, tend to revert to the opposite sex type.  Then he tends to be dwarfed, fatigable, adipose.  Among these types are included subjects of obsessions and compulsions who are dull and apathetic, cannot learn or maintain inhibitions, and so, without initiative, evolve into moral and intellectual degenerates, liable to epilepsy and the most remarkable sex aberrations.  All because a cranny of the skull, about the size of a thimble, is not large enough for their dominating gland.

If the bone of the cavity of the pituitary is softer and yielding, so that some enlargement of the gland is possible, especially of the anterior, there appear rapid growth with a tendency to high blood pressure, great mental activity associated with frequent and severe headaches (often of the migraine type), a combination of initiative and irritability and a marked sexuality.  X-ray examination of the sella turcica shows what is called erosion of the bone as it yields to the pressure of the growing gland.

The ideal sella turcica for the ideal pituitary type is a large room in which the gland may grow and reach its maximum size and so its maximum function, without needing to exert pressure or destroy and erode bone in front of it, to the side of it or behind it.  The distinctive masculine and feminine types, classed as the normal, belong to this group.  Sometimes, the bone in front of the pituitary will yield, while the one in the rear will not, and sometimes the conditions are reversed.  Thus we may have ante-pituitary sufficiency with post-pituitary insufficiency, or ante-pituitary insufficiency with post-pituitary sufficiency, complexes which contribute to create the grosser functional hermaphrodite types of mixed sex.