Feeding of thymus to some of the lower creatures of the animal kingdom will completely hold up differentiation. Take the unfolding of the specialized tissues and organs which transform the tadpole into the frog and the chrysalis into the butterfly. A tadpole kept supplied with enough thymus in a nutrient medium will swell into an extraordinary giant tadpole, but will not change into a frog. Recently, this experiment has been contradicted. Yet this effect corresponds to the conception of its importance in childhood as a retardant of precocity, physical and mental. Clinical observations emphasize that in childhood it is the chief brake upon the other glands of internal secretion which would hasten development and differentiation, checking them perhaps for a given time and so profoundly influencing growth.
THE PINEAL
The pineal is another gland which has been credited with similar abilities and a like holding-the-reins-tight-in-childhood function among the cells. Like the thymus, it has been supposed one of the distinctive organs of childhood and to die with it. Generations of anatomists solemnly asserted, repeating each other's mistakes with the aplomb of the historians who declare that history repeats itself, that the pineal body was a useless, wastefully space consuming vestige of a once important structure. That was the view in that century of grandly inaccurate assertions, the nineteenth. Not that they relegated it with that statement to the limbo of the dull and the uninteresting. Quite the contrary. They conferred upon it a distinguished romance and mystery by identifying it as the last heir 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 story told by his parents was quite extraordinary, even to the jaded palate of the clinic professor and his assistants. They said that he was a little over five years old, a statement conclusively proved correct at his death. Up to the time at which his illness began, he had been quite normal in size, intelligence and interests. But with the onset of his misfortune, he had begun to grow, and rapidly until now he looked and corresponded in all measurements to a normal boy of twelve or thirteen. Hair developed all over his skin, most prominently and abundantly in the typically hairy places of adults. His voice became low-pitched, and most remarkable of all, his sexuality and mentality precocious. He became capable of true sexual life and is said to have asked many questions about the fate and condition of the soul after death. On one occasion he remarked reflectively: "It is odd how much better I feel when I let other children play with my toys than when I play with them myself." Other statements attributed to him imply the most astounding maturity of thought and mental process. Headaches finally came, and he died about four weeks later. The cause of the whole bizarre tragedy was found to be a tumor of the pineal gland.
As has happened before in medical history, no sooner was the one prodigy reported, than a score of others of the same ilk sprang into the limelight. Cases of precocious genital development, especially, some of them occurring as early as the second year of life, were linked with them. It is an interesting point to be noted that in these, as in those started by an overaction of the adrenal cortex, it is premature masculinity that is stimulated. The adrenal cortex must be classed as a gland of masculinity. The pineal possibly acts as a brake upon the adrenal cortex.
Very soon after the report of Von Hochwart's prodigy appeared, an experimental research on the pineal was begun in New York. The pineal glands of a number of young bullocks were obtained and used for feeding, to see whether an overaction of the internal secretion could be produced. Guinea pigs, kittens and rabbits were used. The experiments covered about two years in time. Of a dozen small kittens, the subjects outgrew the controls rapidly in activity, size, intelligence, and resistance to intercurrent disease. Of ten small rabbits, the controls weighed about a third less than the subjects, which were strikingly clean, active, fat and salacious.
Feeding of the gland was then extended to a particular class of defective children, children with well-shaped heads, normal eyes, symmetrically functioning limbs, excellent digestion, strong muscles and generally, normal, sometimes rapid growth. It is to them, particularly when mental normality has progressed up to the eighth, tenth or twelfth year and stopped, that the term "moron" has been applied. They have been a hopeless lot, belonging to the limbo of the incurables. Moreover, they, emphatically the physically normal ones, differ from one another enormously in the extent to which mental operations are possible. As all transitions and degrees exist, no definite classification and subdivision of them has been made. Yet ever since the cretin, once looked upon as an eternally damned defective, was transformed by thyroid feeding into an apparently normal being, there has been no dearth of effort to find the right kind of internal secretion to fit their desperate situations, but in vain. In defectives with definitely, organically damaged brains, no result of course was to be expected. In those of any class over fifteen, no response has been elicited by feeding pineal gland. In the others the results have been contradictory.
A set of observations have related the pineal to muscle function, inviting comparison of it with the thymus. There is a singular muscle shrinking and deforming disease, known as progressive muscular dystrophy, hitherto a complete and unsolved mystery. Newer studies of the pineal in this disease during life by means of the X-ray have shown it calcified, that is, buried in lime salts, which signifies put out of business. Recently thus another hint as to its function has been ferreted out.
The tadpole as a reagent to test out the growth effects of different glands of internal secretion has also been employed for the pineal. Ten-day-old tadpoles fed on pineal present a marked translucency of the skin due to a retraction of the skin pigment cells. Now without a doubt a number of as yet unknown growth and metabolic effects follow exposure of the body to the complete gamut of light rays. The interesting suggestion follows that the pineal influences the body by varying the degree of light ray reaction.