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).
Stoppato also obtained analogous results in infantile atrophy and anemia. Hence it is evident that the very rapid growth in the embryo is associated with the functional action of the thymus. And this is also true of the very rapid growth during the first years of a child's life.
The pituitary gland, or cerebral hypophysis, has also functions associated with the general nervous tone and trophism (or nourishment) of the tissues, and especially of the osseous system. There is a disease known as acromegalia (Marie's disease) which is characterised by an abnormal and inharmonic growth of the skeleton, especially in the limbs and the jaw; the hands and feet become enormously enlarged, while the jaw lengthens and thickens (an unhealthy formation on which the common people of Italy have bestowed the name of "horse sickness," because of the appearance assumed by the face). Such patients complain of general and progressive debility of their psychic activities. In such cases, an autopsy shows an alteration of the pituitary gland, often due to malignant tumors (sarcoma).
The suprarenal capsules also bear a relation to general trophism and particularly to the pigmentation of the skin. It was already noted by Cassan and Meckel that the negro races show a greater volumetric development of the suprarenal capsules; when in 1885 Addison for the first time discovered a form of disease associated with alterations of the suprarenal capsules, characterised by an intensely brown colouration of the skin (bronzed-skin disease), general debility of the nervous and muscular systems, progressive anemia and mental torpor; the malady ends in death. In the case of animals operated on for physiological experiments, not one of them has been able to survive.
Some interesting observations have been made by Zander on the connection between the development of the nervous system and the suprarenal glands. He found that there was an insufficient development of these glands in individuals having teratological (monstrous) mis-shapements of the brain, as in the case of hemicephalus (absence of one-half the brain), cyclops, etc.
There exists between all the ductless glands, or those of internal secretion, an organic sympathy: in other words, if one of them is injured the others react, frequently to the extent of assuming a vicarious (compensating) functional action.
What their functional mechanism is, that is, whether the secretions act as formative stimulants or enzymes, ferments of growth, or whether as antitoxins to the toxins elaborated by various organs in the process of regression, is a question still controverted and in any case cannot enter within the limits of our field.
It is enough for us to know that the general growth of the organism and its morphological harmony, depend not only as regards the skeleton, but equally in relation to the cutaneous system and its pigmentation, the development of the muscles, the heart, the blood, the brain, and the trophic functions of the nervous system, upon some formative and protective action of all these little glands of "internal secretion," with which are associated the psychic activities and even the life itself of each individual, as though within the embryonic crucible there must have been certain substances that acted by stimulating the genetic forces and directing the trophism of the tissues toward a predetermined morphology.
To-day it is held that even the mother's milk contains these formative principles, or enzymes, suited to stimulate the tissues of her own child in the course of their formation; consequently, it produces results which no other milk in all nature can replace.