THE GLANDS: THYROID AND PITUITARY
The glands of internal secretion, the history of which, as tools of
thought, I reviewed in the previous chapter, have each an interesting
evolutionary story. Without some acquaintance with that story, the
rough outline of their physical architecture, and the particular work
they are called upon to perform in the body, no adequate understanding
of their influence upon types of human nature and personality is
possible.
THE THYROID GLAND
This gland consists of two maroon colored masses astride the neck,
above the windpipe, close to the larynx. These are bridged by a narrow
isthmus of the same tissue. They remind one of the flaps of a purse
opened up. The gland has always attracted much attention because its
enlargement constitutes the prominent deformity known as goitre.
To begin with, the thyroid was once a sex gland, pure and simple. In
the lowest vertebrates and in the homologous tissues of the higher
invertebrates, the fractions of the thyroid are intimately connected
with the ducts of the sexual organs. They are indeed accessory sexual
organs, uterine glands, satellites of the sex process. From Petromyzon
upward that relationship is lost, the thyroid migrates more and more
to the head region, to become the great link between sex and brain.
How alive that function still is, is grossly shown by the swelling of
the gland with sexual excitement, menstruation and pregnancy.
Relative to the body weight it is largest in the mammalia, and
smallest in the fishes. It therefore grows larger as the vertebrate
ascends in the scale. It has, in fact, developed in direct proportion
to and side by side with the fundamental, differentiating vertebrate
characteristics. Of these, the possession of a dry hairy skin instead
of a moist or mucus bearing, chitinous skin, the ownership of
an internal bony skeleton and a large skull, and a complicated
development of brain, are the diagnostic signs. Thyroid internal
secretion has a very definite controlling relation to all of them: to
skin, its hairiness, moisture and amount of mucus, to the growth and
size of the bones, especially the bones of the extremities and the
skull, and to intelligence and the complexity of the convolutions of
the brain. Injury to the thyroid, especially in growing animals, is
followed by profound retrogression or arrest of development in skin,
skeleton and brain.
In the fishes and the cyclostomes the thyroid is represented only by
some small scrubby patches, little larger than the heads of pins,
scattered along the aorta, the great blood vessels from the heart, and
out a little way along each gill. It becomes larger and more compact
among the amphibians and reptiles, but still remains quite small.
Large and prominent among the birds and mammalia, it is largest and
most prominent among the primates and man. It is hence permissible to
think of the thyroid as a dictator of evolution, to crown it as the
vertebrate gland par excellence, and to call the typical vertebrate
brand marks secondary _thyroid_ characteristics in precisely the
sense of Darwin classing the horns of cattle as secondary _sexual_
characteristics.
In such enthusiasm for the thyroid as a determinant of evolution, its
pillar of cloud by day and column of fire by night, one should not
forget the other glands of internal secretion. In them all, we may
suppose, Life, tired of inventing merely prehensile, destructive and
reproductive organs, hit upon the happy thought of contrivances which
are in essence chemical factories to speed up the rate of variation
and so of a higher evolution.
CREATOR OF THE LAND ANIMAL
According to this conception the thyroid played a fundamental part in
the change of sea creatures into land animals. Experimentally, thyroid
has been used to transform one into the other. Thus the occasional
change of a Mexican axolotl, a purely aquatic newt, breathing through
gills, into the amblystoma, a terrestrial salamander, with spotted
skin, breathing by means of lungs, has long been known. Feeding the
axolotl on thyroid gland produces the metamorphosis very quickly, even
if the axolotl is kept in water. In the reptile house at the London
Zoological Gardens full-grown examples of the common black axolotl and
the pretty white variety are exhibited. Some are nearly three inches
long. Alongside are shown several examples of the amblystoma stage,
produced in one of the laboratories of Oxford University and at
the gardens by thyroid feeding. A variation of the thyroid in the
direction of increased secretion was probably responsible for the
first land animals.
THYROXIN, SECRETION OF THE THYROID
Under the microscope, as in the test tube, the thyroid shows
remarkable and unique features. Closed spherules lined by a single
layer of cells enclosing a gelatinous material known as colloid, which
stains deeply with acid dyes, comprise the units of its architecture.
Essentially, it may be pictured as a series of jelly bubbles secreted
by outlying cells.
A relatively high percentage of iodine is the unique distinctive fact
in its chemistry. Discovered by Baumann in 1895, the presence of the
element has focused the intelligence of chemists upon the gland,
with the consequent demonstration of arsenic also in it. It was soon
manifest that the secretion of the gland was dependent upon the
iodine content for its activity. Active extracts of the thyroid like
thyreoglobulin and iodothyrin were proven to contain iodine, and to
become inactive when the iodine was removed. Efforts to isolate the
iodine containing active principle in pure form were fruitless until
the work of Kendall at the Mayo Foundation. He obtained it as a white,
finely crystalline, odorless and tasteless substance, heat stable,
and analyzable. The free form separates as a sheaf of fine needles.
Kendall at first called it the a-iodine compound, then named it
thyroxin.
There are other internal secretions of the thyroid, with a function of
their own, that have no iodine. But they are secondary, and obscure.
Thyroxin is accepted today as the purified internal secretion of the
thyroid because all the effects of the whole gland may be elicited
with it. Thyroxin produces results with doses amazingly minute
compared with the quantity of whole gland necessary. Moreover, a dose
of thyroxin appears to last an organism in need of it over a period of
time; the other has to be administered continuously.
Studies with thyroxin carried on in recent years have rounded out the
whole concept of the business of the thyroid in the body economy.
One may sum it up by saying that the thyroid secretion is the _great
controller of the speed of living_. The more thyroid one has, the
faster one lives; the less one has, the more slowly one lives.
That is not to imply any direct proportion between the amount of
thyroid secretion in an individual, and the length of life to which he
is destined. The speed of living, in the chemical sense (which is the
fundamental sense), and the rate at which the chemical reactions go on
that constitute the process of life, are dependent upon the thyroid.
When the reactions go faster, more oxygen and food material are burned
up or oxidized, more energy is liberated, the metabolic wheel rotates
more quickly, the individual senses, feels, thinks and acts more
quickly.
Likening one energy machine to another, the thyroid may be compared
to the accelerator of an automobile. That is a rough and superficial
comparison because an accelerator lets in more of the fuel to be
burned up, while the thyroid makes the fuel more combustible. It thus
resembles more the primer, for a rich mixture of gasoline and air
burns at a greater velocity than a poor one. But the action of thyroid
could really be simulated only by some substance that could be
introduced into the best possible of gasoline mixtures, to increase
its combustibility by a hundred per cent or more. For that is what
thyroid will do to our food. Nor has it only this destructive or
combustion side. Withal there is at the same time a constructive
action, for the process frees energy to be used for heat, motion or
other need. The thyroid, therefore, in addition to its rôle as an
accelerator, acts, too, as the efficient lubricator for energy
transformations. So we see it as accelerator, lubricator and
transformer of our energies.
THE GLAND OF ENERGY PRODUCTION
The isolation of thyroxin has made possible the determination of the
influence of the thyroid hormone upon the evolution of energy in any
higher animal organism. There is, for every individual, a constant,
known as the metabolic rate, or the combustion rate, a reading of the
rate at which his cells are consuming material for heat. The metabolic
rate is thus a gauge of the energy pressure within the organism.
It may be calculated by measuring the amount of carbon dioxide gas
exhaled during a unit of time, and the number of calories of heat
radiated by the skin simultaneously. A simplified device has lately
rendered it practicable to make actual determinations by a few
five-minute readings of the rate of oxygen absorption by the lungs.
Plummer, also connected with the Mayo Foundation, has shown that what
would amount to less than a grain of the thyroxin would more than
double the amount of energy produced in a unit of time. To be exact,
one milligram of thyroxin increases the metabolic rate two per cent.
That illustrates some of the power of the internal secretion of the
thyroid and its importance to normal life.
THE MOBILIZATION OF ENERGY
But not only is the height of pressure of energy in the cells
controlled by the thyroid. The mobility of that energy is also
controlled. Without it, rapid and large fluctuations of energy output,
and elasticity and flexibility of energy mobilization for any sudden
mental or muscular act, let alone an emergency, become impossible. A
woman suffering with myxedema, the condition described by the English
physician Gull as a cretinoid state supervening in the adult life
of woman, has an insufficient amount of thyroxin in her blood and
tissues. She is clumsy and awkward and will stumble when endeavoring
to walk upstairs. Any effort is almost paralyzed because the range
of fluctuation of energy, the ability to mobilize energy, in turn
dependent upon an ability to increase the metabolic rate, is limited.
In slang phrase, she cannot step on it. Her existence is set to go at
a rate in the neighborhood of forty per cent below the normal. By the
administration of thyroxin, her metabolic rate can be raised to any
desired figure, the spark can be adjusted, so to speak, to any point
we like, and it can be so maintained for years.
In the normal animal, to be sure, the internal secretion of the
thyroid is not absolutely essential to life. So it contrasts with the
hormone of the minute parathyroids placed so closely to it, a minimum
dose of which is absolutely a prerequisite for continued life. The
fundamental chemical reactions within the cells occur in the complete
absense of thyroxin. But they go on in a relatively fixed, rigid and
unvarying way, confined within the narrow limits of a constant figure.
Under such conditions, the level of energy production is bound to be
low, and to remain low, and the modus of its mobilization slow and
unwieldy. With thyroid is introduced the trick of _catalysis_, or the
speeding up of the vital chemical reactions, through the agency of an
_intermediate_ which accelerates the process. It is par excellence the
great catalyst of energy in the body. (A catalyst is an intermediary
like the trace of water, which will bring about an explosion between
dry oxygen and hydrogen that without it have stayed inert with the
strongest currents of electricity.) Thus it supplies a mechanism not
only for quantity output of that subtle reality we label energy, but
also an apparatus for varying the available amount of it, and for
permitting the maximum range in ease and rapidity of its utilization.
The thyroid is still another device of life for procuring more and
more variation and differentiation, its goal, as far as we can peer
through the opalescent screen upon which its manifestations quiver.
From another point of view, the thyroid may be looked upon as the
organ evolved for maintaining the same amount of iodine in the blood
as there is in sea water. Sea water was our original habitat, since,
like Venus, we have all come up out of the sea.
The more intimate study of the composition of the blood has revealed
the most astonishing parallelism between it and the compounds of sea
water. The blood is sea water, to which has been added hemoglobin as
a pigment for carrying oxygen to the cells not in direct contact with
the atmosphere, nutrients to take the place of the prey our marine
ancestors gobbled up frankly and directly, and white cells to act as
the first line of defense. To keep the concentration of iodine in the
blood a constant, the thyroid evolved, since there is no iodine in
most foods and very little in those which do contain it.
That a minimum amount of iodine in the food is necessary to health is
shown by the existence of goitre regions. Around some of the Great
Lakes in the United States, for instance, the water does not contain
enough iodine. As a result, numerous cases of goitre occur. Iodine in
the form of sodium iodide in small doses will act as a prophylactic.
The amount of iodine in the blood is about one or two parts to ten
millions, and that of the liver is about three or four parts to ten
millions. Since the liver is the most complex and active chemical
factory in the body, its appropriation of a greater amount of iodine
for itself is understandable.
When thyroxin is administered in a single dose, there is a distinct
lag in the absorption of it by the tissues. A single dose does not
generate its maximum effect until the tenth day. This effect continues
for about ten days. Then there is a gradual decrease in the intensity
of reaction for another ten days. So that the length of time a single
administration of thyroxin functions within the body is about three
weeks. Again we have occasion to notice a protective device of the
cells. Since the presence of thyroxin in the tissues determines the
rate at which they burn themselves up, it is obvious that if there
were no mechanism for retarding its action, and at need varying it,
they really would set fire to themselves. That is to say, if the
tissues held a maximum of the thyroid internal secretion, and had to
take up more and more as it was fed out to them by the thyroid through
the blood, the pressure of energy production would attain the state of
a boiler without a safety valve. Even if self-destruction were avoided
by the ingestion of the largest quantities of energy-bearing foods,
rest for the cells would be difficult, if not impossible.
The thyroxin in the tissues diminishes after a period of great
exertion, the thyroxin probably being carried back to the thyroid
gland and kept there as reserve until further demand. So it has been
discovered that during the winter months, the thyroid glands of beef,
sheep and hogs all contain much less iodine than during the summer
months. During the winter months, manifestly, more energy is required
to maintain body temperature, hence the gland surrenders more of its
secretion to the tissues and so keeps less of it itself. There must
be, too, a certain wearing out of the potency of the iodine with time.
Even dead inorganic catalysts, made of simple elements, wear out after
having been used time and time again.
Though the thyroid is the supreme energizer, life is incompatible with
a certain excess of it. Death can be produced by successive daily
injections of its internal secretion. But it has, besides the
energizing effect, certain formative and nervous influences equally
marvelous. As illustrations, there are the cases of thyroid
deprivation in human beings, cretinism and myxedema, as well as
those in which it is believed there occurs an excess of the
thyroid secretion in the blood and tissues, the condition of
_hyper_thyroidism.
CRETINISM AS THYROID DEFICIENCY
Not that there is any arresting contrast of startling difference
between the phenomena presented by different species. The younger the
animal, the grosser the morbid symptoms witnessed. The animal fails to
grow. The bones and cartilage, except of the skull, fail to develop.
The abdomen projects and becomes large and flabby. The sex organs
atrophy. There is sterility. Pregnant rabbits abort, hens produce
very small eggs or none at all. These are the results of removing the
thyroid in animals.
Apathetic, indifferent, dirty, awkward, apparently idiotic, describe
the human cretins. Their skin is rough and coarse, peeling in sheets.
In some it is considerably knarled and creased as in the aged, and in
others swollen, hard and resistant. The hair becomes shaggy and rough,
losing all luster, and tends to grow irregularly and fall out. The
temperature becomes subnormal and an anemia supervenes. There is a
distinct reduction in the resistance to infections and intoxications.
Cretinism in the human is a condition in which the burning taper we
call Life flickers and smoulders and smokes. Thirty years ago it
was an example of the most hopeless idiocy. Whole populations were
afflicted with it. But neither man of science, nor bigot-fanatic,
assured by the Divine Confidence of its meaning as a visitation,
believed it could be modified an iota. Today, that inept word "cure"
may be applied to our power of attack upon it, provided it is
permitted to attack early enough. Modification, in the direction of
the most surprising betterment, is the miracle that has been wrought.
The history of a cretin runs somewhat as follows: A baby is born,
which in all appearances seems normal. Perhaps the nose is a trifle
squatter than even the average new-born's flat nose. There may also be
abnormal sleepiness, greater even than that of the normal baby in the
first month or two in that there is no spontaneous awakening from
the coma for food. But in most cases this is put down to normal
variability, or maybe to that limbo of all a baby's troubles:
weakness. After some months, it is noticed that the infant is failing
to grow at the normal rate, either physically or mentally. Examination
at this time reveals a curious thickening of the dental ridges. Then
the tongue takes the centre of the scene, by becoming unusually thick
and prominent, to the point of projecting beyond the mouth at all
times, and interfering with breathing, when the infant is in a
recumbent position.
More and more of the characteristics of the affection turn up. The
queer, repulsive, pitiful face of the cretins, which makes them all
seem brothers or twins, shapes itself. A yellowish, white or waxy
pallor; rough, dry, scaly, bloated skin; swollen, often wrinkled brow;
watery eyes, often almost concealed by the thickened eyelids; the
depressed pug nose with its wide, thick nostrils; large, erect ears;
the wobbly, drooling tongue, sticking out at one, yet not in derision;
the hair thin, and like tow in texture rather than human; eyebrows
and eyelashes are scant, and often absent; the nails short, thin and
brittle; the teeth, very late in coming, may be represented by a few
sharp points, irregular, decaying quickly, sometimes not succeeded at
all by those of the second dentition.
Whatever growth occurs is irregular and disproportionate. The trunk,
though small compared with the head, appears massive against the
background of the diminutive extremities. The back is somewhat humped,
arching at the waist-line, while the abdomen protrudes like a balloon,
with a hernia, often, at the navel. The extremities are short, bowed,
cold, and livid, covered with rolls of the infiltrated skin, rolls
which cannot be smoothed out. Hands and feet are broad, pudgy, and
floppy, the fingers stiff, square and spade-like, the toes spread
apart, like a duck's, by the solid skin. Above the collar bones there
are frequently great pads of fat which sometimes encircle the narrow
bull neck.
The mental state varies with the degree of deprivation of the internal
secretion of the thyroid. In the worst cases it is repulsively
vegetable. Even the intelligence common to the higher animals is
wanting. The cretins of the "human plant" kind, as they have been
nicknamed, will not recognize mother or father or any person about
them, or even a person from an object, and manifest no interest in
anything or anybody, not even toys. Hunger and thirst they manifest by
grunts and inarticulate sounds, or by screaming. They neither smile,
cough, nor laugh, but sit like sphinxes, breathing, but not reacting.
There are, of course, all grades and varieties. There are those who
recognize parents and familiar faces, and exhibit some evidence of
affection for them, acquire a limited vocabulary, and then cease, no
progress possible even with the alphabet. They attain the size and age
of two or three years and there stop altogether, as if a permanent
brake were applied to the wheels of their growth. Some higher types
may even come to speak connected sentences, and exhibit a certain
mild spontaneity, though stupid and slow and abnormally deliberate,
resembling the acquired form of thyroid deprivation or insufficiency,
for which Ord invented the name myxedema.
I have filled in with some detail this thumbnail sketch of thyroid
deprivation as it occurs in infancy to illustrate how wide a sweep the
gland's lariat embraces. Skin, hair, bones, muscle and fat, brain and
intelligence, growth and development, are modified precisely as the
size and shape of certain crystals are modified by the presence or
absence of ingredients in an apparently homogeneous solution. A
fertilized ovum, in which the predecessor of the thyroid gland is
present, that is to say, in which there is the seed and soil for its
sprouting, looks the same as one without that formative material. Yet,
when the time comes for the internal secretion of the thyroid to put
in its oar in the metabolic game, its presence or absence makes all
the difference in the world to the individual.
In the middle of the nineteenth century, when the concentration of
phosphorus in the brain was established as significant, the cry for
the emphasis of that fact was--without phosphorus no thought is
possible. We can much more relevantly declare that without thyroid,
no thought, no growth, no distinctive humanity or even animality is
possible. For the epigram about phosphorus was bombast, since it can
be declaimed with equal truth that without oxygen, without carbon,
without nitrogen, without any of the food elements that go to make
up the chemical composition of brain matter, no thought is possible.
Indeed, if one were set upon the indictment of a single chemical
element as the begetter of consciousness, the prisoner at the bar
would have to be copper. There is more copper in the brain by a
considerable degree than in any other organ of the body. Which perhaps
will be exceedingly regretted by the patrons of the aristocracy of the
soul who would have it as an emanation of a deposit in the brain of
silver at least, if not gold. They are like the old lady who would
never permit herself to be cured of her ailments except by gold plated
pills. Copper, however, is not necessary to intelligence. Without
thyroid there can be no complexity of thought, no learning, no
education, no habit-formation, no responsive energy for situations,
as well as no physical unfolding of faculty and function, and no
reproduction of kind, with no sign of adolescence at the expected age,
and no exhibition of sex tendencies thereafter.
EFFECTS OF FEEDING THYROID
How subtly the internal secretion affects every phase and aspect of
child as well as adult, by doing something to the speed of activities
in their cells, is told straightway by the effects of it when eaten
or introduced into the skin or blood of various people. A cretin,
idiotic, dwarfish, deformed, hopeless, an incessantly prodding burden
of sorrow to the mother, who looks upon the masterpiece she had
labored to bring forth, and beholds a terrible gargoyle, becomes
transformed when fed thyroid.
In a few days the cretin will get warmer, and require much less
wrapping and bed-clothing. With the improvement in circulation, the
color becomes better and the extremities lose their coldness. In a
week or so, irritability and resentment at disturbance appear. He will
begin to recognize and know his parents, smile and play. There is
a gradual return to the normal of the facial appearance, and a
resumption of growth. All kinds of marvelous growth effects occur.
Twenty teeth may be cut in six months. Coarse, rough dry, shaggy hair
becomes fine, silken, long and curly. The skin becomes soft, moist and
roseate. Inches in height may be added every month. Bright, active,
even talkative, are the descriptive terms an observer would apply
after a few months. A complete remaking of body and soul is apparently
affected.
Yet, should the administration of the thyroid cease, an almost
immediate reversion to the original vegetative condition is
inevitable. After a few days, reactiveness slows down, the child will
speak only when spoken to, will sit quietly in a chair all day and
act semi-anesthetized. Gradually hair and skin return to the previous
cold-blooded animal state, and the whole picture of the cretin is in
full bloom. Supplying the internal secretion of the gland promptly
repeats the transformation.
One wonders what is to be the ultimate fate of these reformed cretins.
Since the tale of the opening of life to them, once considered
hopeless idiots, is scarce a generation old, we have no data, as
yet, as to the character of their children or grandchildren, their
adventures and vicissitudes, in short, their life history. Those of
whom we have any record are normal and healthy school children or
workers, alive to the interests of childhood or their occupation
and social circles. No one outside their family knows that they are
cretins, and the most acute observer would be hard put to it to
suspect. What a theme for the reflections upon appearances the eminent
Victorians loved!
There are possibilities the imagination may envisage. One may suppose
such a cretin, with all his other ductless glands intact, grown
successfully to manhood under careful medical guidance. No one but
himself is aware of his affliction, outside of his medical advisers.
Luck aids him to rise in the world, or perhaps he has been born with
a spoon of the precious metals in his mouth. Adolescence, love and
marriage dance their sequence. Our hero of course keeps his dread
secret to himself. Whether such an omission of confidence would
entitle his wife to a divorce is something courts will be called upon
to decide sooner or later. But, without anticipating, the honeymoon
involves a trip to the South Seas. A storm and a wreck throws them
alone on an island, tropical, easy to live on, and rescue in the
course of a few months certain. The man, to his horror, discovers that
he has saved of his medicaments only a pill box containing half a
dozen of thyroid tablets, his requirement being one a day. He sees
them go day by day. Finally they are all gone. He feels his faculties
slipping hour by hour. Shall he tell her? Indecision grips him, and he
delays until the day when his consciousness sinks to the point where
his mind no longer grasps his problem. The wife must endure the
spectacle of the enchantment of her husband, and his change from
gallant lover to dull animal ogre. A new version of Beauty and the
Beast!
Cretinism as one manifestation of a soul without thyroid or without
enough thyroid is not all. The first great successes with thyroid were
achieved in adults, particularly adult women, exhibiting a peculiar
obesity, coldness, loss of hair and teeth and a remarkable lassitude
and torpor that might be summed up as a chronic drowsiness, like a
saturation of the blood with some narcotic drug. Or there may be a
melancholia, or a lack of ability to seize the finer points of a
mental process, or an argument treated in the abstract. Children
are said to be lazy, slow or dull. They experience an irritating
difficulty in understanding questions and expressing their wants and
desires, and so are declared to be vicious, or stupid.
All these are grades of the degeneration which Ord, the Englishman,
named myxedema. At its worst it is a sort of bloating and drying of
the body and the mind. Then there is infantilism, which is helped by
the giving of thyroid extract. It differs from the ordinary cretinism
in that, while one is reminded of the latter by the physical stunting
and the other stigmata, there is a certain amount of intelligence
which enables the individual to hold his own while he is a child. He
becomes a grown-up baby: at twenty prefers the company of children of
ten, and passes under the evil influence of designing so-called normal
persons. So dominated he will lie, steal, start fires, commit almost
any crime, with no inherent flair for criminality, but because of a
lack of independent judgment and inability to resist suggestion, and
a desire to please friends. He is simply an overgrown child who still
loves to play with toys, laughs and cries, becomes angry or afraid,
unreasonably and ridiculously, and yells for mamma when thwarted or
scared.
So much for what happens when there is not sufficient of the thyroid
secretion in the blood and tissues. Now to consider the effects of
an excess of it, the condition called hyperthyroidism, as the
insufficiency of it is labelled subthyroidism. Too much thyroxin can
be introduced into the system of a normal individual, or even a cretin
by the simple administration of too large doses or over too long
a time. Also a train of symptoms similar to those evoked by an
oversecretion of the thyroid may be mobilized by the taking of too
much iodine. Great sorrow, great joy, a sudden severe jolt to the
nervous equilibrium, sexual excitement, an overwhelming anger or grief
may leave in their wake a permanent hyperthyroidism. The symptoms are
the reverse of cretinism and myxedema. There is an over-excitability
of the nerves in place of sluggishness, and an over-reactivity of the
whole organism to its environment. The heart's action is too fast, and
under the slightest stimulus gets faster to the point of obtruding
itself into the conscious mind as a palpitation. Instead of the
lowered temperature and coldness of the cretin, there is a heightened
temperature, one or two degrees above the normal, and a feeling of
heat. The individual has a high warm color, does not sleep well,
becomes or remains thin no matter how much he or she eats, is
abnormally susceptible sexually, may suffer from a definite insomnia,
is emotional, and perspires freely. Alert, neurotic or high-strung,
magnetic, and imaginative are some of the descriptive adjectives
applicable. The eyes are bright and prominent, large and beautiful,
when they have not reached the stage entitled "pop-eyed." Or they may
even become so protuberant and bulging as to develop the expression of
one staring aghast at some ineffable horror. The latter is the feature
of only the severest types, when there is an associated goitre, the
combination designated as exopthalmic goitre.
There are, too, individuals in whom hyperthyroidism and hypothyroidism
are mixed, or rather alternate. At one time they present the phenomena
of the one, at another of the other. They are the people who complain
of the cyclic quality of their moods and purposes. Their mood will
be a heaven of exaltation and exhilaration, and then descend into a
slough of despond from which they feel themselves inextricable. They
are always talking about the ups and downs of their mental states.
Headache and languor and fatigability, dry skin and lack of appetite
for food or exertion on one day or for one week, give way on the next
day, or for the next week, to an energetic gayety, and sweaty, flushed
skin, a prominent appetite for food and every sort of activity. Driven
to be forever on the go, for one period, in the next they feel like
lying down most of the day, with no inclination for any life whatever.
The stage of depression may go as far as a melancholia, the stage of
stimulation as far as mania. They may simulate manic-depressive or
cyclic insanity. Something restrains them, and holds them bound as in
a vise in the one cycle. And then they are driven on beyond themselves
by some invisible whip in the next.
THYROID AS DIFFERENTIATOR
Besides the action of the thyroid as energizer, lubricator, and growth
catalyzer, it has a remarkable power as a differentiator of tissues.
It determines the embryonic etchings of the different organs which in
their totality comprise the unique individual. Every multicellular
animal must first have existed as a single cell, the impregnated ovum.
With the body and personality of the ovum, the creature is one and
continuous, literally something the single cell has made of itself by
sub-dividing and differentiating. In the process, the cell mass often
goes through stages which stand out as individualities in themselves,
that appear on the surface absolutely unrelated. So the caterpillar
and the butterfly, to the naïve child, seem as far apart as worm and
bird. In the case of the frog, the tadpole as a first sketch seems
completely an impossible and wild absurdity. Yet we know that there is
an orderly progression of events, a propagation of cells, a forward
going arrangement of chemical reactions, that results in expansion and
intricate complication of the organism. Just what the forces at work
in this most mysterious of all natural processes are, has been an
intellectual mystery that the best minds of the race have attempted
to get rid of with words like pangenesis (Darwin). Words of Black
(Mediterranean or Greek and Latin) origin, as Allen Upward has named
them, always cover a multitude of ignorances. The glands of internal
secretion, here, as in so many other dark places, provide the open
sesame to certain long closed doors of biology. They offer themselves
to us as the first definitely tangible agents which are known to keep
the process of growth going, and undoubtedly initiate the marvelous
unfolding of tissues and functions, organs and faculties summed up as
development or differentiation.
Thus by the direct feeding of thyroid at particular points in the
differentiating history most curious effects have been elicited. If
the gland is made part of the nutriment, the bathing environment, of
the tadpole, a hastening of its metamorphosis is attained. The tadpole
lives not out its day as a tadpole, but precociously turns into a
frog. But such a frog! It is a miniature frog, a dwarf frog, a frog
seen by looking through the wrong end of the telescope, a frog not
magnified, but micrified. Frogs have been so created the size of
flies. There has occurred a splitting of the two reactions which
ordinarily go hand in hand: the reaction of growth which is just brute
increase of total mass or weight and volume, and the reaction of
differentiation which is the finer process. The picture is a frog, but
a frog the size of a tadpole, a frog which has missed its childhood,
adolescence and youth, skipping over these transition stages into the
adult age, as a pigmy.
It is all as if a baby were suddenly to grow a beard and moustache,
evolve and shed teeth, and acquire the manner of an earnest citizen,
and yet retain the height and weight of a baby. That the spectacle
of such a superbaby is not quite the most fantastic of all
improbabilities is shown by the condition of progeria, first recorded
by the Briton, Hastings Guilford. A queer spectacle in which a child
incontinently grows old without having lived--in the course of a few
weeks or months. You look upon him and see senility on a small scale,
but with all its peculiarities: wrinkled skin, apathy, gray hair and
all the rest of it. All we can say about it is that it is probably due
to a paralysis of all the glands of internal secretion, a removal
of their influence upon the cells. Contrariwise to the feeding of
thyroid, removal of the thyroid of tadpoles will prevent their
development into frogs. If iodine is then fed to them, say mixed with
flour, normal metamorphosis will occur. If Body is the tool chest
which we carry about with us, as Samuel Butler said, then to the
thyroid belongs the name of tool-maker.
Another function of thyroid that must be taken into consideration is
what has been spoken of as its antitoxic function--in plainer English,
its power to prevent poisoning, or to increase resistance against
poisons, including the bacteria and other living agents which
cause the infectious diseases. Each molecule of food, ingested for
assimilation into our substance, accumulates a history of wanderings
and pilgrimages, attachments and transformations beside which the
gross trampings of a Marco Polo become the rambling steps of a
seven-league booted giant. In the course of its peregrinations, it
becomes a potential poison, potential because it is never allowed to
grow in concentration to the danger point. The thyroid plays its rôle
of protector like all the internal secretory machines. In an animal
deprived of a thyroid the feeding of meat shortens life--a single
sample of how it works to guard against intoxication from within. The
feeding of thyroid will also raise the ability of the cells to stand
poisons introduced from without--intoxications of all sorts. Alcohol
and morphine will affect in much smaller doses the subthyroid person
than the normal or the hyperthyroid. As regards the infections, which
directly or indirectly kill most of us, the injection of thyroid will
increase the content in the blood of the protective antibodies which
preserve us, temporarily at any rate, against malignant invaders. The
opsonins, for example, those substances which butter the bacteria so
that the appetite of the white cells for them is properly roused, are
mobilized by thyroid feeding or injection. Other substances in the
blood which destroy and dissolve bacteria are also increased. The
thyroid probably performs these functions by sending its secretion
to the cells directly responsible for the immunity reactions, and
stimulating them to activity.
A sketch of the thyroid like the foregoing shows it as the wondrous
controller of vitality and growth, and indefatigable protector against
intoxicants and injuries. When it is sufficiently active, life is
worth while; when it is defective, life is a difficult threatening
blackness. That would make it out as the gland of glands. It is
tremendously important, without a doubt, in normal everyday life. But
no more so than the other members of the cast. The position of star it
may claim, but in vain. The other glands of internal secretion to
be sketched will each, when the marvels of its business in the
cell-corporation are considered, present itself as candidate for the
honors of the president. Justice should give fair credit to all
the organs which fabricate the reagents of individuality, and the
regulators of personality.
THE PITUITARY
In the human skull, the pituitary is a lump of tissue about the size
of a pea lying at the base of the brain, a short distance behind the
root of the nose. It is of a grayish-yellow color, unpretentious and
insignificant enough in appearance, and so long neglected by the
scientists who boast their immunity to the glamor of the spectacular.
Guesses at its nature date back to Aristotle.
Like most of its colleagues among the glands of internal secretion,
it is really two glands in one, two glands with but a single name. At
least it consists of two different parts, distinct in their origin,
history, function and secretions, but juxtaposed and fused into what
is apparently a homogeneous entity. They are conveniently spoken of as
the anterior gland and the posterior gland.
In the embryo, the anterior gland is derived by a proliferation of
cells from the mouth area. The posterior gland represents an outgrowth
of the oldest part of the nervous system. When it is traced back along
the tree of the vertebrate species, it is found to be present in all
of them. An ancient invention, its precursor has been identified in
worms and molluscs and even among the starfish. "The pituitary
is practically the same, from myxine to man." A trusted veteran,
therefore, among the internal secretory organs, its importance can be
surmised.
To understand the story of the pituitary, variously acquired bits of
information concerning it have been assembled and fitted together like
the fragments of a picture puzzle, as Cushing has so well put it. Here
and there pieces stick out, obviously out of place. The relations of
some of them to one another or to the whole design are not at all
clear. Parts appear to have been irrevocably lost, or not yet to have
turned up. Chance bystanders will select odd figures and articulate
them into a new harmony. Yet out of the jumble of fragments, a fairly
respectable insight has been gained in less than a half century.
The pituitary is cradled in a niche at the base of the skull which,
because of its form, is known as the Sella Turcica or Turkish saddle.
So situated, an operative approach to it is overwhelmingly difficult.
On the other hand, X-ray studies are favored. "Nature's darling
treasure" it might be called, since there has been provided a skull
within the skull to shelter it.
Under the most highly magnifying lenses of the microscope, three kinds
of cells have been distinguished. The anterior gland is a collection
of solid columns of cells, surrounded by blood spaces into which their
secretion is undoubtedly directly poured. A gelatinous material,
presumed to be the internal secretion of the gland, has, in fact, been
observed emerging from the cells into the blood spaces. The posterior
lobe, or gland, consists of secreting cells producing a glassy
substance which finds its way into the spinal fluid that bathes the
nervous system. The spinal fluid itself is a secretion of another
gland at the base of the brain, the choroid. Nerves and internal
secretion are associated here with a closeness symbolic of their
general relations.
From each portion of the gland (to stick to the accepted nomenclature
of speaking of the two glands as one) an active substance has been
isolated. Robertson, an American chemist, separated from the anterior
lobe a substance soluble in the fat solvents, like ether and gasoline,
which he christened tethelin. But P.E. Smith has shown that the active
material is soluble neither in boiling water nor in boiling alcohol,
the typical fat solvent. A number of facts favor the idea of the
anterior lobe cells as stimulants of growth of bone and connecting
and supporting tissues generally. From the posterior lobe, pituitrin,
believed its internal secretion, has been obtained in solution.
Pituitrin is a substance of many marvelous functions. In general, it
controls the _tone_ of the tissues, of involuntary or smooth muscle
fibres of the blood vessels and the contractile organs of the body
like the intestines, the bladder and uterus. When injected, it will
slowly raise the blood pressure and keep it raised for some time, and
will increase the flow of urine from the kidneys and of milk from the
breasts. It will also cause an intense continued contraction of the
bladder and the uterus. It is also said to control the salt content of
the blood upon which its electrical conductivity and other properties
depend. Normally, there is a certain fixed ratio of the salts in the
blood, which keeps them like the ratio in sea-water. Again, we have
an example of the curious atavism of the internal secretions. The
thyroid, remember, keeps the iodine concentration of the blood like
that of the ocean, our original habitat. Pituitrin likewise does its
part to maintain our internal environment as near as possible to what
was once the surrounding medium. A substance somewhat similar has been
found in the skin glands of toads.
The extraordinarily well protected position of the pituitary, its
persistence throughout life, and its abundant blood supply, emphasize
its vital importance. No other gland of internal secretion can
adequately substitute for it. Complete expiration means death, in two
or three days, with a peculiar lethargy, unsteadiness of gait and loss
of appetite, emaciation, and a fall of temperature, so that the
animal becomes cold-blooded, its temperature the same as that of the
atmosphere it occupies. If only part of the anterior lobe is taken
away, there occurs a remarkable degeneration of the individual. The
degeneration is not a mucinous infiltration of the skin and the
internal organs which occurs with thyroid deprivation, but a fatty
degeneration, with a tendency to inversion of sex. A singular
somnolence, a dry skin, loss of hair, a dull mentality, sometimes
epilepsy, and a noticeable craving for and tolerance of sweets appear.
These are but a few of the observations obtained in experimental
sub-pituitarism, that is, underaction or insufficient secretion of the
pituitary, produced by removing part of the anterior gland.
If such an experimental sub-pituitarism is started in infancy, for
instance in puppies, there is a cessation, or marked hindering and
slowing of growth. That is, dwarfs are artificially created. Apropos,
pathologists have shown that in several true human dwarfs the gland
is rudimentary or inadequate. All of which goes hand in hand with the
evidence that the skeleton stands directly under the domination of the
pituitary.
REGULATOR OF ORGANIC RHYTHMS
There are certain other singular by-effects of the gland in its
relation to the periodic phenomena of the organism like hibernation,
sleep, and the critical sex epochs of both sexes. In hibernation, or
winter sleep, the animal in cold weather passes into a cataleptic
state in which it continues to breathe, more deeply but more slowly
than when awake, but shows no other signs of consciousness or life.
A lowered blood pressure and a marked insensitivity to painful and
emotional stimuli go with it. There is a preliminary storage of starch
in the liver, and of fat throughout the fat depots of the body. These
are so like what happens after part of the pituitary is removed, that
a comparison of the two becomes inevitable. Common to both conditions
is a drop in the rate of tissue combustion or metabolism, which can
be relieved by injection of an extract of the pituitary, a rise of
temperature occuring simultaneously. Moreover, examination of the
glands of internal secretion of hibernating species, like the
woodchuck, during the period of hibernation, shows changes in all of
them, but most marked in the pituitary, the shrunken cells staining
as if they too were asleep, or in a resting stage. The characteristic
alive qualities of these cells return, without relation to food
or climate, when the animal comes to in the spring, at the vernal
equinox. Hibernation may, perhaps, be put down to a seasonal wave of
inactivity of the pituitary gland.
Now winter sleep may be looked upon as an exaggeration of ordinary
night sleep, the latter differing from the former only in its brevity.
In the natural sleep of non-hibernating species there occurs, too,
a fall in temperature. Moreover, they all, even man, have a certain
capacity for winter sleep, as the experiences of travellers and
explorers in the arctic regions indicate. In certain parts of Russia,
where there is a scarcity of food during the winter months, the
peasants pass weeks at a time in a somnolent state, arousing once a
day for a scant meal. Just as the sex glands influence the body and
mind profoundly with a certain cyclic periodicity of activity and
inactivity (rut, heat, menstrual period and so on), which has been
demonstrated to have a very close functional relationship with the
pituitary, so sleep and hibernation will bear interpretation as
products of a temporary dormancy of the same gland. We have, then,
to set up in the place of Morpheus and Apollo, the new gods of the
internal secretion of a chemical-making bit of the brain, as an
explanation of the rhythms of sleep and wakefulness.
There are individuals who go about outside of hospital walls,
quasi-normally, who are semi-hibernators or partial hibernators, and
who are really in a state of subpituitarism. They are people who may
have something wrong or inferior with their pituitary, but not to the
extent of interference with their daily life. They go about with their
type stamped upon them for the seeing eye. The classical type is
obese, with fat distributed everywhere, but more so in the lower
abdomen and the lower extremities. They are slow and dull, and
sexually inactive, often impotent. They are sometimes tall, but most
often dwarfish, and may be subject to epileptic seizures. They recall
the picture of what happens to young dogs partially deprived of the
pituitary. Dickens delivered a perfect likeness of an extreme degree
of the condition in the Fat Boy of the "Pickwick Papers," whose
employment with Mr. Wardle consisted in alternate sleeping and eating.
WHEN THE PITUITARY OVERACTS
All grades of overaction of the pituitary exist. Then its peculiar
power to act as a stimulant to the growth of bone and the soft
supporting and connecting tissues like tendons and ligaments comes
into play. If the overaction or excess of secretion begins in
childhood or adolescence, that is, before puberty, there results a
great elongation of the bones, so that a giant is the consequence. Now
giants have always appealed to the imagination of the little man, and
have had all kinds of wonderful abilities ascribed to them by him. The
giants and ogres of folk-lore and fairy tales are favored with the
most extraordinary mental advantages. Direct and analytic acquaintance
with the giants of our own day, as well as a probing of their conduct
in the past, has shown that normal giants--persons of exceptional size
free from physical or mental deformities--are rare. There are people
with _hyper_-pituitarism who exhibit the highest mental powers. In
them is an increased activity of the posterior lobe in association
with enlargement and hyperfunction of the anterior, overgrowth is not
so marked, and the individual is lean and mentally acute. But the
ordinary giant is one in whom there is degeneration of the pituitary
after too much action of the anterior and too little of the posterior
glands. A tumor or disease process in the gland is most often
responsible.
If the overaction of the anterior happens after puberty, when the
long bones have set, and can not grow longer, a peculiar diffuse
enlargement of the individual occurs, especially of his hands and feet
and head. The nose, ears, lips and eyes get larger and coarser.
As these people are rather big and tall to begin with, the effect
produced is that of a heavy-jawed, burly, bulking person, with bushy
overhanging eyebrows, and an aggressive manner. For there is, too,
something distinctive about their mentality which has been as often
portrayed as those of the pathologic giant. Rabelais' most famous
character, Gargantua, belongs to the group. We recruit more
drum-majors than prime ministers from among these people. They
often suffer much from torturing boring headaches, and a consequent
despondency and feeling of hopelessness which colors gray the entire
spiritual spectrum. Up to a certain point these sufferers have a
remarkable alertness and capacity. When conscious of the malady, they
often meet it with a doggedly courageous optimism, which is another
characteristic, although women occasionally commit suicide.
In both the semi-hibernators who remind one of cattle, and in the
giant or acromegalic types who remind one of the anthropoid ape, there
develops a distinct diminution of sexual life. An abnormal process in
the anterior gland, whether of oversecretion or of undersecretion,
may interfere with the proper functioning of the posterior gland, the
secretion of which is tonic not only to the brain cells, but also to
the sex cells. Thus, young animals deprived of the pituitary will not,
if male, grow spermatozoa, nor ripe ova in the female. Moreover, the
feeding of pituitary increases sexual activity. In the case of hens,
this has been demonstrated to be about thirty per cent by a pretty
experiment. At a time of the year when eggs diminish, six hundred
and fifty-five hens laid two hundred and seventy-three eggs upon an
ordinary diet. When pituitary was added to their food for four days,
the number of eggs rose to three hundred and fifty-two, an increase of
seventy-nine. In addition, the fertility of the chicks born of these
eggs was augmented, especially if both parents had been fed on
pituitary. There are other aspects of the relation of the pituitary to
sex, which will be treated in another chapter.
THE BONY CRADLE OF THE PITUITARY
Always, in attempting to understand the pituitary, it is necessary to
remember that it is tightly packed in the bony cradle, the Turkish
Saddle or Sella Turcica. Should some stimulus, local, or in the blood,
arouse the gland to growth, a good deal will depend upon whether it
has room to grow in, or it will make room by eroding the bone. With
space for the formation of a large anterior and posterior pituitary
gland, there will be created the long, lean individual, with a
tendency to high blood pressure and sexual trends, great mental
activity, initiative, irritability and endurance. An outstanding trait
of these favorites of fortune is that they remain thin no matter how
much food they consume, and they have the best of appetites. They
often are subject to severe headaches because of intermittent swelling
of the gland against the bone of its container.
If the bony container is or becomes too small for its contents, it
is interesting that along with the other signs of pituitary
insufficiency, such as undersize, obesity, and asymmetry, there
developes conspicuous moral and intellectual inferiority. The
unfortunates suffer from compulsions and obsessions and lack
inhibitions. They are the pathological liars with little or no
initiative or conscience--amoral, not merely theoretically, but
instinctively and unconsciously, with all the certitude and perfection
of the unconscious accomplishment.
THYROID AND PITUITARY
The thyroid and the pituitary have often been compared. The anterior
gland and the thyroid arise from almost the same spot in the embryonic
oesophagus, the thyroid being an outgrowth in front, the anterior
pituitary an outgrowth behind of the same soil. They both control
growth marvelously, also the differentiation, the mass and intricacy
of the tissues. But they differ in the site of their control. The
thyroid bears more directly upon the inner and outer coverings of the
body, the skin, the skin glands and the hair, the mucous membranes,
and the irritability and the preparedness for response of the nerves.
The pituitary acts more upon the framework of the body, the skeleton
and the mechanical supports and movers. Bone and ligament, muscle
and tendon seem to be within its immediate sway. The secretion or
secretions of the pituitary diffuse directly into the fluid bathing
the nervous system, supplying beneficent stimulants and aiding in the
abstraction of harmful waste. So while the thyroid raises the energy
level of the brain, and the whole nervous system, as a byproduct of
its general awakening effect upon all the cells of the body, the
pituitary probably stimulates the brain cells more directly, perhaps
in the manner of caffeine or cocaine.
The difference between the thyroid and the pituitary might be put this
way: that while the thyroid increases energy evolution and so makes
available a greater supply of crude energy, by speeding up cellular
processes, the pituitary assists in energy transformation, in energy
expenditure and conversion, especially of the brain, and of the sexual
system. In short, the thyroid facilitates energy production, the
pituitary its consumption. The pituitary appears therefore as the
gland of continued effort. Hence fatigability, an inability to
maintain effort, is one of the prominent complaints when there is
destruction or an insufficiency of it for one reason or another. As
such, it contrasts with the glands of emergency effort, known as the
adrenals.