Page:Popular Science Monthly Volume 86.djvu/147

Rh injection of adrenalin, by excision of the pancreas or by a lesion of the islands of Langerhans in that organ. On the other hand, an increased tolerance for carbohydrates (obesity) occurs after destruction of the posterior lobe of the pituitary body, as well as in myxœdema or after thyroidectomy; increased blood pressure follows upon injection of the pituitary, adrenal, placental and kidney extracts; lactation is accelerated by injection of extracts of the thymus, pineal and pituitary bodies and the corpus luteum (ovary); the pupil is dilated by extracts of the thymus, pituitary, pancreas, suprarenals, kidney, sexual glands, liver and muscle. Effects of this kind are analogous to the mystifying "enharmonic cross relations" in modern music, in which the same note (on the piano scale) is so employed that it is brought into relation with two different tonalities. C sharp and D flat, G sharp and A flat produce the same sounds when given on the piano scale, although they can, if necessary, be distinguished on stringed instruments, which render an exact account of the difference in the number of vibrations. Similarly, these apparently identical effects of the different ductless glands indicate that their functions are correlated, that they are somehow concerned in maintaining the hormonic equilibrium of the body.

Concerning the mechanism of correlation, two prominent theories have been advanced. The first is the doctrine of the hormones of Bayliss and Starling (1902) in which the chemical control of the body is assumed to be effected by means of hormones, or chemical messengers, which pass from the various organs and ductless glands, via the bloodstream, to other parts of the body, producing biochemical effects upon irritable protoplasmic tissues. In the initial experiment of Bayliss and Starling, the secretion of pancreatic juice following upon introduction of acid into the duodenum was found to be not a local reflex, as had hitherto been assumed, but due to the action of a hypothetical substance (secretin) discharged by the intestinal mucous membrane under the influence of the acid and carried to the pancreas by the blood channel. Many experiments, particularly those of Howell on the coagulants and anticoagulants of the blood (thromboplastin and antithrombin) indicate the existence of hormones. Adrenalin, iodothyrin and pituitrin are the only hormones of the ductless glands which have been isolated to date.

The other theory is that of the clinicians and pharmacologists of the Vienna school, Eppinger, Falta and Rudinger, which asserts that the suprarenal and thyroid bodies act upon and are controlled by the nerves of the sympathetic system, while the pancreas is similarly related to all nerves acting upon smooth (involuntary) muscle and not originating from the chain of sympathetic ganglia. The two systems have been termed "autonomic," because they seem to be detached from and independent of the controlling impulses arising from the