Part 2

THE NATURE OF GLANDS

The human body contains many thousands of glandular structures, some large, some small, some simple, some complex, but all of them absolutely essential to its proper growth and health. Some of these organs which are most familiar are the sweat glands through the skin, the salivary glands of the mouth, the gastric glands of the stomach, the liver, the kidneys, the pancreas, and the male and female reproductive glands. Except for those of reproduction, the glands in this list are not to any especial extent connected with personality. Of course, if they do not function correctly, the health is impaired and changes in temperament result. But that much can be said of any other physiological organ. For the most part these glands of external secretion, as they are called, each has its own specific function to perform. They take up certain substances from the blood stream, or from the intestinal tract, transform them and then emit them through well defined ducts. In this manner the kidneys secret urine, the liver bile, the gastric glands gastric juices. The ducts or tubes which carry the transformed substances to the exterior are essential parts of the glands, themselves, and the secretions are always ejected through them.

There are, however, other glandular structures in the body which have no definite outlets. The substances which they secrete do not pass out through well defined passages but are absorbed directly by the blood stream. Their effect is the same as that of drugs injected into the blood by a hypodermic needle. In fact, if the chemical constituent of a ductless gland’s secretion is known and can be prepared in the laboratory, the same results can be got through its artificial injection as from the increased activity of the gland itself.

THE FUNCTION OF THE ENDOCRIN GLANDS

It is these ductless glands, or endocrin glands, or glands of internal secretion (they are known by any one of these names) which especially concern us when we speak of the effect of glands on personality. Besides the ovaries and testes, which give off an internal as well as an external secretion, they include the thyroid and parathyroid glands of the neck, the thymus gland in the chest, the adrenal glands situated just above the kidneys, and the pineal and pituitary bodies both located within the cranium close to the brain.

Because these organs have no visible outlets, it was only within comparatively recent times that they were supposed to have any function at all. Or if a purpose was assigned to them, it was usually highly fantastic and without any basis in fact. Thus the thyroids, which can be easily felt at the lower part of the neck on each side of the trachea, were supposed to keep the larynx moist and so produce a dulcet singing voice. But the thyroids, on account of their conspicuous position, are the glands about which we have the fullest information.

Because the secretions of the endocrin glands flow directly into the blood stream and are therefore carried very quickly to all parts of the body, their exact location is of slighter importance than might at first be thought. Because the pineal and pituitary bodies happen to be situated within the skull, they do not necessarily have a peculiar effect upon the brain. In fact, the thyroid in the neck probably is more closely connected with mental development than either of them. And the function of the pineal is more like that of the thymus than it is that of its nearer neighbor, the pituitary.

The thymus and the pineal. Broadly speaking, we may say that the thymus and the pineal are the glands which control childhood. Both are present and well developed at birth but continue to grow and expand for some years later. Each ceases to grow at puberty when the sexual glands become active. In normal individuals the pineal body disappears entirely after adolescence and very little is left of the thymus subsequent to this period.

The internal secretion of the reproductive glands. Simultaneously with the atrophy of the thymus and the pineal body, the internal secretion of the reproductive glands, which up to this time have been dormant, commences and puberty sets in. The chief effect of the endocrin activity of the testes and ovaries lies in the development of the secondary sexual characteristics. In this connection the investigations of Steinach are the most authoritative as well as the most widely known. His experiments proved conclusively that it is not the reproductive elements proper but the interstitial cells of Leydig, which lie within the larger sex glands, which furnish the internal secretion. Professor Howell sums up Steinach’s primary investigations as follows:

“Making use of very young animals (Steinach) has transplanted the testes from their normal position to other regions. Such animals develop normally, show all of the usual secondary sexual characteristics, and manifest full sexual desire and potency at the proper period. When the transplanted glands are examined the sexual elements are lacking, but the interstitial cells are increased in amount. It would appear from this work that sexual puberty is dependent upon the internal secretion furnished by these cells, and Steinach proposes to designate them collectively as the ‘puberty glands.’ This observer reports further remarkable experiments in which young males (rats, guinea pigs) were first castrated and then had transplanted under the skin or in the peritoneal cavity the ovary from a female of the same species. Under such conditions the graft of the ovary takes, and unlike the grafted testicle both the reproductive cells and the interstitial cells survive. In such animals the secondary male characteristics do not develop, his genital organs remain infantile; he exhibits, on the contrary, the female characteristics, as shown by his size, the character of the hair, and especially by the development of mammae and nipples. So far as the external characteristics are concerned the animal is completely feminized, and Steinach states that such an animal is sought by the male as though it were a true female.”

Working with very old animals, Steinach has further proved that by splitting the seminal duct, thus blocking the external secretion of the testes, the interstitial cells can be made to function more vigorously and a temporary rejuvenation, a sort of second adolescence, can be produced.

Not all of the phenomena usually associated with puberty are, however, caused directly by the activity of the reproductive endocrin glands. Many of them are effected by the interstitial secretions stimulating to greater activity other ductless glands, namely, the pituitary, the adrenals and the thyroid.

The thyroids and parathyroids. So tightly are the parathyroids imbedded in the thyroids in all carnivorous and omnivorous animals, that many fatal operations were performed before it was discovered that the two are separate, if not completely independent organs. Goiters, which are always either enlargements of the thyroids, themselves, or of the connecting tissue surrounding the thyroids, can be easily eliminated by making a small incision in the neck and cutting away the superfluous tissue. In certain geographical regions where the soil contains very little iodine (the most important element in thyroid secretion) the thyroids, in an attempt to overcome this deficiency, grow abnormally large and endemic goiters result. In the country surrounding the Great Lakes of America and in the valleys of Switzerland such goiters are common. Often they are not large enough to be especially dangerous or conspicuous, but in some individuals they attain an enormous size and, of course, their possessors are anxious to have them reduce. Soon after the introduction of medical surgery, many beautiful Swiss ladies went into Paris to have their unbecoming tumors removed. And about half of those who were operated upon died within a few days. The rest recovered and showed no ill effects of their experience. Physicians were at a loss to account for the fatalities. But as animal experimentation was making headway, an explanation was soon forthcoming from the physiological laboratories.

The laboratory investigators discovered that if both thyroids were removed from carnivorous animals the subjects were within a few hours seized by severe convulsions and soon died. Herbivorous animals, on the other hand, lived for a long time after complete thyroidectomy, although they exhibited profound changes in what might be termed their personalities. Anatomical examinations showed that in all carnivorous and omnivorous animals the four tiny parathyroids are imbedded in the thyroid, while in herbivorous species two of the parathyroids are separated from and lie outside of the larger gland. From this it was decided that the thyroids, although they are most important to proper development, are not essential to life, while the parathyroids, through the cancelling effect they have upon various poisons continually given off by the body, are. In the case of the unfortunate Swiss beauties, the parathyroids had been inadvertently cut away with parts of the thyroids in those who succumbed to the operation, but were left intact in those who survived.

The function of the thyroid. The thyroid is the endocrin gland about whose function we have the most complete information. Diseases of the thyroid, in particular goiters, are far from uncommon and the effects of these diseases have been carefully studied. Also the chemical constituents of the thyroid secretion has been determined and an artificial thyroid extract is now easily manufactured. This has been widely used in animal experimentation and as a human therapeutic. In normal individuals the thyroid glands function throughout life. In children they are necessary both to normal physical growth and to proper mental development. In adult life they are essential to body metabolism and mental stability.

The pituitary and the adrenals. Although the adrenal and the pituitary is each a single gland, both of them have two well defined parts. As in the case of the parathyroids and the thyroids, the anterior lobe of the pituitary and the cortex of the adrenals are essential to life, while the medulla of the adrenals and the posterior lobe of the pituitary furnish the secretions which have the more pronounced effect on the personality. Unlike the parathyroid, however, the life-essential portions of each of these glands is intimately connected with sexual development.

The chemical properties of the secretion produced by the medulla of the adrenal glands are known and form the basis of the drug called adrenalin. The effects of this drug have, of course, been carefully studied. The two most important results of an artificial injection of adrenalin lie in a strong stimulation of the nerves which control the heart, the blood vessels and the muscles; and an increase in the amount of sugar in the blood. Translated into more general terms, which will be explained in detail later, this means that the adrenals regulate our emotions as the thyroids do our mental life. And the posterior lobe of the pituitary body, in much the same manner, controls the muscles and skeletal bones directly.

From this brief outline of the role of the various ductless glands it should be evident that a well balanced person, a thoroughly normal individual, is one whose endocrin system is nicely attuned. His every gland secretes just enough but not too much. From the interstitial cells of his sexual glands he gets his secondary sexual characteristics, which until he reaches adolescence were kept in abeyance by his thymus and his pineal. His thyroid keeps his brain active; his pituitary body his muscles well toned; his adrenals his circulation well regulated and his emotional apparatus ready for emergencies. But, let us see what happens to an individual when one particular gland is either more or less active than it properly should be.

GLANDULAR ABNORMALITIES

The effects of heightened or lessened secretion of the sexual glands can be easily predicted. Abundant and very active interstitial cells cause the completely masculine man or the entirely feminine woman. When these cells are greatly reduced in number or dormant in their function, the sexual types are not so pronounced and approach each other in secondary characteristics. It is not until this condition becomes complicated by derangements of other ductless glands that it becomes definitely abnormal, but any variation in any one of these other organs is more than apt to have a direct effect on the reproductive system. This is shown clearly in the case of the thymus and the pineal.

The pineal gland, as we have seen, is essentially a gland of childhood. If both his pineal and his thymus are functioning normally then a child will be like other children. He will grow and develop gradually until he reaches his teens when the more drastic changes of puberty commence. It is at this time that his pineal body should cease to function and begin to atrophy. But suppose, for some reason, it begins to atrophy when he is only about six or seven years of age. What happens then? The child begins to grow remarkably, his reproductive organs develop, his figure becomes like that of an adult and he shows a strange mental precocity. This is the classical type of the child prodigy. And it was the pineal gland about which so much was said in the Leopold-Loeb murder trial.

If the pineal body continues to function well into the teens an individual who is almost the exact opposite of the one just described develops. Puberty is delayed for a long while――probably indefinitely. The child never grows up either anatomically, sexually or mentally.

The abnormal history of the thymus gland is similar to that of the pineal, but with a few slight differences. While the pineal and the thymus both act reciprocally with the sexual glands, they also have some check upon each other. It may be said in general that while both of these glands function in lieu of sexual secretion, the thymus allows the child to grow to its full stature while the pineal protects him from growing too rapidly. (It was to be borne in mind, however, that both of these glands of childhood control growth indirectly, as we shall see when we come to study the pituitary in more detail.) Accordingly then, if a child has an insufficient thymus, his growth is stunted, his bones do not harden properly, he is subject to rickets and to malnutrition, he is apt to become either very fat or very thin; and there is a corresponding retardation of mental growth.

If the thymus continues to be active after the age at which puberty normally occurs, the results are more striking even than they are when this gland is insufficient during childhood. In this case the child proceeds to grow, but he grows only as a child. His reproductive organs do not develop and he acquires none of the characteristics which typify adolescence. Human beings of this class are not rare, but on account of the striking changes which occur when a tadpole matures, that is when its metamorphosis into a frog takes place, the result of a prolonged activity of the thymus is illustrated more clearly in the case of this animal than of any other.

Tadpoles fed upon a continual diet of thymus extract will not change into frogs. They remain tadpoles, but tadpoles of tremendous size. And a eunuch who has been castrated just before adolescence has, essentially, a tadpole personality. Because his interstitial cells never become active, no check is put upon his thymus. Instead of atrophying, it continues to enlarge. Consequently a eunuch is apt to be very tall, possibly also babyishly plump, but he undergoes none of the usual adolescent transformations. His voice remains high pitched, he does not grow a beard and all of his other characteristics remain almost completely childlike.

If thyroid extract is fed to young tadpoles an effect which is the exact opposite of that produced by thymus feeding results. The tadpoles do not grow, but metamorphosis into frogs takes place when they are still very tiny. Frogs scarcely larger than a fly can be developed in this manner. Thus it appears that not all of the processes usually associated with puberty are caused directly by the sexual glands, but rather by the internal secretions of these glands stimulating others to greater or lesser activity.

The thyroid, however, is essential to normal development in childhood and later life as well as at adolescence. In children an insufficient amount of thyroid secretion produces a state of arrested development known as cretinism. Cretins are familiar figures in all feeble-minded institutions. They are small in stature, their skin is rough and coarse, their features are flat and characterless, and their tongues large and thick. They are awkward, unkempt and lazy. Mentally they are classified as idiots. Since the discovery of the active principle of the thyroid――thyroixin――cretinous children, if treated early enough, exhibit signs of marked improvement. They grow, they become more energetic and their mentality approaches more nearly to the normal.

When an insufficiency of thyroid extract occurs after adolescence, the disease known as myxedema sets in. Persons afflicted with this malady show definite and characteristic symptoms. Their hair begins to fall out, their skin becomes moist and swollen and they suffer continually from exhaustion. Most noticeable of all is a pronounced mental deterioration. This disease is commonly caused by an abnormal growth of the tissues surrounding the thyroid. This enlarged tissue crowds in upon the gland and causes it to shrink in size. It cannot under these conditions secrete the amount of extract necessary to bodily health, and myxedema results. The disease can be helped to some extent by regular doses of thyroixin and a permanent cure can be effected by an operation through which the superfluous tissue is removed and the thyroid allowed once more to resume its natural size.