THE ADRENAL BODIES 975 



produced by it may be either an augmentation or an inhibition in 

 accordance with the structural characteristics of the effector so affected. 

 This also implies that the reaction thus ensuing, is practically identical 

 with that induced by the stimulation of the sympathetic fibers them- 

 selves. As has been stated above, the action of adrenalin is made 

 possible through the intervention of a special receptor substance. 

 Thus, Meltzer^ has shown that adrenaUn administered intravenously, 

 dilates the pupil, while its direct instillation into the conjunctival sac 

 is not followed by this reaction unless the superior cervical ganglion 

 has been removed beforehand. This agent may also be employed to 

 determine the constrictor power of the different blood-vessels. In 

 illustration of this statement it might be mentioned that its injection 

 into the cerebral circulation gives a positive reaction, while its injection 

 into the pulmonary circuit does not. The inference to be derived from 

 these tests, is that the blood-vessels of the brain are equipped with a 

 vasomotor mechanism, while those of the lungs are not. 



Inasmuch as the smooth muscle tissue of the walls of the intestine 

 is supplied with inhibitory fibers from the sympathetic division of the 

 autonomic system, adrenalin must cause a loss of its tonus and a 

 disappearance of intestinal peristalsis. A similar effect is produced 

 by it upon the walls of the stomach, gall-bladder and urinary bladder. 

 In the case of the pregnant uterus of the cat, it gives rise to a contrac- 

 tion, but to a relaxation in the non-pregnant organ. The vas deferens 

 and seminal vesicles are contracted, while the plain musculature of the 

 bronchioles is relaxed. It also possesses a relaxing influence upon the 

 blood-vessels of cardiac^ and striated muscle tissue.^ It stimulates 

 the activity of the sahvary and lacrimal glands. 



In addition to these effects upon the neuromuscular and neuro- 

 glandular substance, adrenalin also influences the metabolism of the 

 different food stuffs, chiefly of the carbohydrates. This deduction is 

 based upon the fact that its administration gives rise to the condition 

 of adrenalin-glycosuria, for the obvious reason that it interferes in 

 some manner with the oxidation of the sugars. Its point of attack, 

 however, has not been definitely ascertained, although it has been 

 stated by Underhill and Closson^ that it activates the sympathetic 

 fibers regulating the formation of dextrose from glycogen. Others, 

 again, believe that it influences the liver cells directly, causing them 

 either to discharge a more abundant amount of dextrose or to hinder 

 them in their storage of glycogen. At all events, adrenalin mobilizes 

 dextrose, but certainly not by evoking a greater production of sugar 

 from proteins or fats. Consequently, the condition of adrenalin- 

 hyperlgycemia and glycosuria cannot be directly related to diabetes 



1 Am. Jour, of Physiol., ix, 1903, 252, and ibid., xi, 1904, 28. 



2 Gunn, Quart. Jour. Exp. Physiol., vii, 1913, 75. 



3 Hoskins, Gunning and Berry, Am. Jour, of Physiol., xli, 1916, 513. 



4 Ibid., xvii, 1900, 42. 



