DUCTLESS GLANDS i47 



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 glyco- 

 surias following injection of adrenalin or following increase of the 

 adrenal function from stimulation of the sympathetic system. Hyper- 

 thyroidism (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 inhibi- 

 tory 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 in- 

 creased 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 exci- 

 sion of the posterior lobe of the pituitary will persist even after sub- 

 sequent 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 Abder- 

 halden'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., 



ABC A-C-B B-A-C B-C-A C-A-B C-B-A. 



In like manner, from linkage of four amino acids, 24 structurally iso- 

 meric 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. AVe 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 thermod}Tiamic equilibrium? And here we have another 

 problem which may be described as transcendental. In the ordinary 



