SECRETION OF THE DUCTLESS GLANDS. 799 



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,t 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- 

 celerated, while the blood-pressure is increased sometimes to an 

 extraordinary extent. These results are obtained with very small 

 doses of the extracts. Schaefer states that as little as 5 mgms. 

 of the dried gland may produce a maximal effect upon a dog weigh- 

 ing 10 kgms. The effects produced by such extracts are quite tem- 

 porary in character. In the course of a few minutes the blood- 

 pressure returns to normal, as also the heart beat, showing that the 

 substance has been destroyed in some way in the body, although 

 where or how this destruction occurs is not known. According to 

 Schaefer, the kidneys and the adrenals themselves are not respon- 

 sible for this prompt elimination or destruction of the active sub- 

 stance. Several observers have shown satisfactorily that the ma- 

 terial producing this effect is present in perceptible quantities in 

 the blood of the adrenal vein, so that there can be but little doubt 

 that it is a distinct internal secretion of the adrenal. J Dreyer has 

 shown, moreover, that the amount of this substance in the adrenal 

 blood is increased, judging from the physiological effects of its in- 

 jection, by stimulation of the splanchnic nerve. Since this result 

 was obtained independently of the amount of blood-flow through 

 the gland, Dreyer makes the justifiable assumption that the adrenals 



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



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



j" American Journal of Physiology," 2, 203, 1899. 



