THE ADRENAL GL VNDS 71. 



splanchnic nerve before it reaches the adrenal gland. This !. rait, 



which is the most Important in the present connection, was, ho not 



observed when the blood of the inferior vena cava was prevented by the 

 application of a clamp from '_r<-t t i 1 1 -_r to the heart, but immediately ap- 

 peared, after stimulation, when the clamp was removed This experim 

 taken alone docs not, however, justify the conclusion that th< i any 

 direct relationship between the adrenal glands and the thyroid, because 

 there are in the thyroid gland structures such as the muscle fibers in the 

 blood vessels, which a hypersecretion of epinephrine might affect Bet 

 any direct relationship between the two glands could be claimed to exist, 

 it would bo necessary to show that the thyroid action current is obtained 

 with a concentration of epinephrine in the blood lower than that affecting 

 the blood vessels. 



2. With the Sexual Glands. As mentioned above, a very direct rela- 

 tionship exists between the development of the sexual glands and that of 

 the suprarenale, particularly the cortex of the glands. In addition to the 

 evidence above furnished, it may be mentioned that in hyperplasia of the 

 adrenals changes occur in the testicles, particularly in their interstitial 

 celK 



3. With the Liver. — Of the many functions of this gland that which is 

 most directly associated with epinephrine is the production of glue 



from glycogen— the glycogenolytic pr ss see page 669 . The injection 



of epinephrine causes an immediate discharge of such an excess of irlncose 

 into the blood that hyperglycemia and glycosuria immediately follow. 

 This result is most striking when the injection is made in glycogen-rich 

 animals. In animals from which all the glycogen of the liver lias been 

 removed by starvation, the injection of large amounts of epinephrine 

 causes glycogen to accumulate in the liver cells a result which it is 

 difficult to interpret. 



In the lighl of the facl that stimulation of the greal splanchnic nerve 

 causes a demonstrable increase of epinephrine in the blood, ;1 natural con- 

 clusion is that the glycosuria and hyperglycemia which are known to re- 

 sult from stimulation of the splanchnic nerve or of its center in the 

 medulla, must be dependent upon a hypersecretion of epinephrine. 

 Evidence supporting this hypothesis seemed to be furnished by the obs< 

 \ation that, after the removal of the adrenal glands, stimulation 



splanchnic or of the BO-Called "diabetic" center in the fourth vent! 



no longer produced glycosuria even in a glycogen-rich animal. Bui it is 

 difficult to sec how such an important physiological proci ss as that of the 

 nerve control of the production of sugar by the liver should be depend 

 on the hypersecretion of the adrenal gland, i illy si; pineph- 



rine would have to be carried by the blood around a considerable part 



