SECRETION OF THE DUCTLESS GLANDS. 877 



brain, the lungs, and the heart. On the same generalization it will 

 be noted that plain muscle receiving inhibitory fibers from the 

 sympathetic autonomic system ought to exhibit a relaxation instead 

 of a contraction when acted upon by epinephrin. This, in fact, 

 seems to be the case. The plain muscle in the intestinal walls 

 receives inhibitory fibers from the sympathetic autonomies 

 (splanchnics), and on this musculature epinephrin does cause loss 

 of tone and relaxation instead of contraction, and another beautiful 

 example of the same kind is obtained from the iris. The dilator 

 muscle of the iris is supplied by nerve-fibers from the sympathetic 

 autonomies, and in correspondence with this fact the epinephrin in 

 very minute doses causes a dilatation of the pupil. On the plain 

 muscle in other organs epinephrin has a somewhat variable effect, 

 differing with conditions or with the animal selected. The uterine 

 musculature, for example, in the pregnant cut is made to contract, 

 but in the non-pregnant condition it shows relaxation. The plain 

 muscle of the bronchioles exhibit relaxation under the influence of 

 the epinephrin, and since these muscles probably receive their 

 nerve-supply through the bulbar autonomies (vagus) their reac- 

 tion to epinephrin indicates that the above generalization in regard 

 to the sympathetic autonomies must not be understood to mean 

 that the epinephrin acts only on the musculature innervated by the 

 sympathetics, but rather that the muscle so innervated shows a 

 special response to epinephrin action. Even skeletal muscles are 

 distinctly affected by epinephrin. Under the influence of appro- 

 priate doses, the contractions are increased in size and the subse- 

 quent relaxation seems to be more rapid and complete. In addi- 

 tion to its influence on the muscular or neuromuscular mechanisms 

 epinephrin has an effect upon the body metabolism, especially as 

 regards the carbohydrates. When injected it causes an output of 

 sugar in the urine, which may last for some days. Evidently the 

 epinephrin, in these overdoses, interferes in some way with the 

 sugar-regulating mechanism of the body. Along with the glyco- 

 suria there is hyperglycemia, that is, an increase in the sugar- 

 content of the blood, and the usual explanation for this action of 

 the epinephrin is that it stimulates the process of glycogenolysis, 

 the process by which the stored glycogen of the liver is converted to 

 sugar and given to the blood. This production of epinephrin 

 glycosuria has been observed not only under experimental condi- 

 tions, but also under what may be called normal conditions in which 

 there is evidence of an increased secretion or hypersecretion of the 

 gland. Cannon has described, for example, what he calls emotional 

 glycosuria, a condition in which in consequence of emotional 

 excitement there is an increased secretory activity of the adrenal 

 gland and an accompanying glycosuria. Results of this kind would 



