SECRETION OF THE DUCTLESS GLANDS. 775 



ism. According to the other point of view, less generally held, the 

 function of these bodies is to neutralize or destroy toxic substances 

 formed in the metabolism of the rest of the body, as the liver, for 

 instance, destroys the toxic character of the ammonia compounds 

 by converting them to urea. On this theory the removal of the 

 thyroid tissues results in the accumulation of toxic substances in 

 the blood and the animal dies by a process of auto-intoxication. 



Cyon's View of the Function of the Thyroid. Cyon in numerous 

 publications has advocated a different view of the function of the thyroids. 

 These bodies have a very large vascular supply, and this author assumes that 

 this area serves as a vascular shunt or flood-gate to protect mechanically 

 the circulation in the brain. The dilatation of the thyroid area under con- 

 ditions that threaten congestion of the brain is effected reflexly by means 

 of the hypophysis cerebri and the vagi. For details of this mechanism and 

 also of the supposed effect of the thyroid secretion on the irritability of the 

 centers innervating the heart and blood-vessels see " Archives de physiologie, " 

 1898, p. 618. 



Adrenal Bodies. The adrenal bodies or, as they are frequently 

 called in human anatomy, the suprarenal capsules belong to the 

 group of ductless glands. It was shown first by Brown-Sequard 

 (1856) that removal of these bodies is followed rapidly by death. 

 This result has been confirmed by many experimenters, and so far 

 as the observations go the effect of complete removal is the same 

 in all animals. The fatal effect is more rapid than in the case of 

 removal of the thyroids, death following the operation usually in 

 two to three days, or, according to some accounts, within a few 

 hours. The symptoms preceding death are great prostration, mus- 

 cular weakness, and marked diminution in vascular tone. These 

 symptoms resemble those occurring in Addison's disease in man, 

 a disease which clinical evidence has shown to be associated with 

 pathological lesions in the suprarenal capsules. It has been ex- 

 pected, therefore, that the results obtained from thyroid treatment 

 of myxedema might be paralleled in cases of Addison's disease by 

 the use of adrenal extracts, but so far these expectations have not 

 been completely realized. Oliver* and Schaefer, and, about the 

 same time, Cybulski and Szymonowicz,| discovered that this organ 

 forms a peculiar substance that has a very definite physiological 

 action, especially upon the circulatory system. They found that 

 aqueous extracts of the medulla of the gland when injected into the 

 blood of a living animal have a remarkable influence upon the heart 

 and blood-vessels. If the vagi are intact, the adrenal extracts cause 

 a very marked slowing of the heart beat together with a rise of blood- 

 pressure. When the inhibitory fibers of the vagus are thrown out 

 of action by section or by the use of atropin the heart rate is ac- 



* " Journal of Physiology, " 18, 230, 1895. 



t " Archiv f. die gesammte Physiologie, " 64, 97, 1896. 



