eir and vestigial remnant of
a third eye, situated in the back of the head, which may still be
observed in certain reptiles. Imagine it! Somewhere, stuck away in a
cranny of the floor of your head and mine, is this descendant of an
organ that once sparkled and shone, wept and glared, took in the stars
and hawks and eagles, and now is condemned to eternal darkness and an
ineffectual sandiness. Today, we have not discarded that view of its
history, but we know a little more regarding its composition and
function.

What and where is the romantic object? It is a cone-shaped bit of
tissue hidden away at the base of the brain in a tiny cave behind
and above its larger colleague, the pituitary. Microscopic scrutiny
reveals that it is made up in part of nerve cells containing a pigment
similar to that present in the cells of the retina, thus clinching the
argument for its ancient function as an eye. But the outstanding and
specifically glandular cells are large secreting affairs, which too
reach back to the tidewater days of our vertebrate ancestors, when
Eurypterus and other Crustaceans were engrossed with the fundamental
problems of brain versus belly. Besides these, there are the singular
masses upon which has been fastened the unnecessarily opprobious
epithet of brain sand. These, noted and commented upon from the
earliest times, consist of collections of crystals of lime salts,
sometimes small, lying about in discrete irregular masses, and
sometimes grouped into larger mulberry-like concretions, varying
much in size. These brain sand particles have become of practical
importance in the detection of pineal disease because they, like all
lime salts, will stop the X-rays, and so can be photographed.

For a long time, indeed up to scarcely more than a few decades or so
ago, the pineal was believed to have no present function at all, or at
least no ascertainable or accessible duty in the body economy. That
it might perhaps be, in a sense, a gland of internal secretion was
a despised theory. Then a classic case, the most extraordinary and
curiosity-piquing sort of case, with symptoms involving the pineal
gland, in a boy, was reported by the German neurologist, Von Hochwart.
That boy provoked a little army of researches. He came to the clinic
complaining about his eyes and other troubles which pointed pretty
definitely to a brain tumor as the diagnosis to pigeon-hole him.
Nothing extraordinary about him in that respect. But the