The pancreas is an organ with both an internal and external secretion. The external secretion, long known, evolved by the major portion of the gland, is poured into the small intestine to play the star in digestion. Scattered here and there among the definitely glandular cell groups creating the external secretion are smaller collections of cells, called the islets of Langerhans, which have been demonstrated to elaborate the internal secretion. There are about a million of these islands in each gland. The hormone has been called insuline. Unlike most of the glands with a double secretion in which the internal is absolutely independent, and so to speak, unconscious of the external, these two of the pancreas are often disturbed together, perhaps because trouble easily hits them both together. Quite the most well-known disease due to disturbed internal secretory function of the pancreas is diabetes. An enormous amount of work has been spent upon the various aspects of it as a mystery. Hundreds of papers in a dozen languages upon the subject are in existence. In a nutshell, they have established pretty well that diabetes is a disease in which there is an excess of sugar in the blood and urine because of an insufficient amount of the secretion of the islands of Langerhans in the pancreas. Removal of the pancreas makes the body, essentially the liver, unable to retain sugar, as well as unable to burn up sugar for energy. The situation is comparable to a locomotive with its coal bins leaking, and the coal itself acting as if made of slate or some equally uncombustible or only partially combustible material. The control of sugar mobilization from the liver, where it is stored as glycogen or animal starch, is divided between the pancreas and the adrenals, the pancreas acting as the brake, the adrenals as the accelerator of the mechanism. Adrenal and pancreas are therefore direct antagonists, the pans of the scale which represents sugar equilibrium in the organism. Diabetes may be regarded as a disturbance of the adrenal-pancreas balance, assisted by events which produce adrenal overwork like great or prolonged emotion, or by strain of the pancreas, effected by over-eating for example. There are other minor glands of internal secretions. But those considered are by far the most important and the most recently explored. In a summary, one would classify them as follows: _Name Secretion Function_ 1. Thyroid Thyroxin Gland of energy production Controller of growth of specialized organs and tissues--brain and sex