Page:Popular Science Monthly Volume 86.djvu/151

Rh glycogen of the liver, the normal inhibitory action of the pancreatic hormone being removed, and is thus at once a positive adrenal diabetes and a negative pancreatic diabetes. This harmonizes with the glycosurias following injection of adrenalin or following increase of the adrenal function from stimulation of the sympathetic system. Hyperthyroidism (exophthalmic goiter) produces a tendency to glycosuria from relative pancreatic insufficiency and increased adrenal activity. Myroedema or the corresponding removal of the thyroid gland produces an increased tolerance for carbohydrates (obesity) because the inhibitory function of the pancreas is removed and adrenal action diminished. There is a lowering of carbohydrate tolerance after parathyroidectomy. The lowered carbohydrate tolerance in hyperpituitarism and the increased tolerance in hypopituitarism, demonstrated by Gushing, is explained by the inhibitory action of the secretion of the posterior lobe of the pituitary on the pancreatic hormone, mobilization of glycogen and glycosuria resulting when the pituitary secretion is in excess and the restraining influence of the pancreas thus impaired. Gushing and Jacobson found that the obesity or high sugar tolerance following excision of the posterior lobe of the pituitary will persist even after subsequent excision of the pancreas, no glycosuria developing.

The question arises, how do the internal secretions or hormones act upon the central nervous system? Here we encounter what Ehrlich calls that obscure province of physiology, the specific irritability of organized tissues, or the capacity of protoplasm to react to chemical and other stimuli. If a chemical substance in the blood comes in contact with the chemoreceptors or special groups of atoms in the periphery of a cell, the two sets of substances may remain inert in relation to each other, they may combine, producing equilibrium, or they may induce a vigorous reaction through difference in their chemical potentialities. The complexity of this phase of the subject is fairly indicated in Abderhalden's studies of intracellular metabolism, in which he shows that by linkage of three different amino acids. A, B, C, the following isomeric arrangements can be produced by permutation and combination, viz.,

In like manner, from linkage of four amino acids, 24 structurally isomeric compounds may result, from five, 120; from six, 720; from seven, 5,040; from fifteen, 1,307,674,368,000; from twenty, 2,432,902,008,176,640,000. We have as yet no calculus of variations fine enough to estimate even the rate of change of these evanescent combinations, which we may assume, are constantly taking place within the cell.

Again, it may be asked, is the hormonic equilibrium of the body identical with thermodynamic equilibrium? And here we have another problem which may be described as transcendental. In the ordinary