THE ADRENAL GLANDS 789 



2. With the Sexual Glands. As mentioned above (page 768), a very 

 direct relationship exists between the development of the sexual glands 

 and that of the suprarenals, particularly the cortex of the glands. In ad- 

 dition to the evidence already furnished, it may be mentioned that, in hyper- 

 plasia of the adrenals changes occur in the testicles, particularly in their 

 interstitial cells. 



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

 most directly associated with epinephrine is the production of glucose 

 from glycogen the glycogenolytic process (see page 701). The injection 

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

 into the blood that hyperglycemia and glycosuria immediately follow. 

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

 animals. In animals from which all the glycogen of the liver has 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 light of the fact that stimulation of the great splanchnic nerve 

 causes a demonstrable increase of epinephrine in the blood, a 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 obser- 

 vation that, after the removal of the adrenal glands, stimulation of the 

 splanchnic or of the so-called "diabetic" center in the fourth ventricle 

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

 difficult to see how such an important physiological process as that of the 

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

 on the hypersecretion of the adrenal gland, especially since the epineph- 

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

 the circulation before it arrived at the place on which it was to act. More- 

 over, it has been shown that stimulation of the previously cut hepatic 

 nerve plexus (around the hepatic pedicle) in a normal animal produces 

 hyperglycogenolysis, in which case there can be no question of a hyper- 

 secretion of epinephrine. 



No doubt the adrenal glands have some important relationship to the 

 nerve control of the glycogenolytic process, for, in animals from which the 

 adrenal glands have been removed, stimulation of the hepatic plexus does 

 not produce hyperglycemia. From this result it would appear that the 

 presence of a certain amount of epinephrine in the blood i& necessary for 

 the proper transmission of the nerve impulse from the sympathetic nerve 

 fibers to the liver cell. When the nervous system is stimulated in such 

 a way as to excite the glycogenolytic process, two effects both operat- 



