These glands are very small; the largest is the thyroid, which weighs between thirty and forty grams (1 to 1-3/5 oz.); the suprarenal glands weigh four grams each (about 60 grains); the hypophysis hardly attains the weight of one gram.
The importance of these glands began to be revealed when antiseptic methods rendered surgery venturesome, and the attempt was made (in 1882) to remove the thyroid gland. After a few weeks the patient operated on began to feel the effects of the absence of an organ necessary to normal life: effects that may be summed up as, extreme general debility; pains in the bones and in the head; an elastic swelling of the entire skin; enfeebled heart action, and anemia; and on the psychic side, loss of memory, taciturnity, melancholy. After the lapse of some time the patient showed such further symptoms as the shedding of the cuticle of the skin, whitening of the hair and _facies cretinica_.
But when Sick undertook to operate upon the thyroid of a child of ten, the deleterious effects of interrupting the above-mentioned function of the gland manifested itself in an _arrest of_ _development_; at the age of twenty-eight the patient operated on by Sick was a cretin (idiotic dwarf) 1.27 metres tall (average stature at age of ten=1.28 m.). Since that time certain diseases have been recognised that call to mind the condition of patients who have undergone an operation for removal of the thyroid glands, and in which the subjects have suffered from _hypothyroidea_, or insufficient development of the thyroid.
Such individuals were characterised by _nanism_, solid edema of the skin, arrest of psychic development, and absence of development of puberty; this malady has taken its place in medical treatises under the name of myxedema; and, when serious, is accompanied by _nanism_ and myxedematous idiocy. But in _mild_ _cases_ it may result in a simple myxedematous infantilism.
The other glands of internal secretion are also associated with the phenomena of growth. First in importance is the _thymus_ which is found highly developed in the embryo and in the child at birth, and thereafter diminishes in volume, until it almost disappears after the attainment of puberty. In the psychological laboratories of Luciani, at Rome, the first experiments were conducted upon dogs, for the purpose of determining what alterations in growth would result as a consequence of the removal of the thymus. The dogs thus operated on were weak; furthermore they became atrophied, accompanied by roughness of the skin and changes in pigmentation. After this, experiments were made in the Pediatric Clinic at Padua, under the direction of Professor Cervesato, in the application of thymic organotherapy (that is, the use of animal thymus as medicine) with notable success in the case of atrophic children (infantile atrophy occurs in early infancy; this form is known popularly in Italy as the "monkey sickness." Nursing children become extremely thin, cease to grow in length, the little face becomes elongated and skeleton-like, and is frequently covered with a thick down).