158 GROWTH 



tex, or its experimental hypof unction, as we at present believe, 

 which leads to the death of the animal. But clinical and patho- 

 logical evidence, especially the presence of tumors of the adre- 

 nal cortex, indicate that overgrowth of the cortex is associated 

 with the overdevelopment and character of the secondary sexual 

 growths. The masculine or feminine features, the beard and 

 growths of hair on the body are all expressions of form depend- 

 ing in part on the amount of secretion of the adrenal cortex. 

 The evidence is derived from cases of overgrowth of this organ. 

 The condition of virilism, Figure 82, has been associated in nu- 

 merous instances with the presence of tumors of the suprarenal 

 cortex and the corresponding overfunction. Surgical removal 

 of the tumor is followed, as in the case figured, by slow return 

 to the feminine features, loss of the beard and recovery of nor- 

 mal feminine functions. 



We know in detail what the hormone from the adrenal 

 medulla does in terms of physiological reaction. It stimulates 

 an increase in function of all those nervous mechanisms which 

 we call the sympathetic autonomics. Of course this is a technical 

 explanation, but everyone can realize that under certain condi- 

 tions the heart rate is enormously increased, that the size of the 

 small blood vessels may be increased or decreased as in blushing 

 or in sudden pallor, and that the motility of the stomach and 

 intestinal tube under certain conditions seems to be augmented, 

 or relaxed beyond all normal limits, that the pupil of the eye 

 is widely dilated, or that the hairs "stand on end." These are il- 

 lustrative of the control by the sympathetic nervous system of 

 physiological conditions. We call these reactions autonomic be- 

 cause we have absolutely no individual voluntary control over 

 them. We are often conscious of the fact that they are operating 

 but we cannot by any conscious effort change the reactions as we 

 do those of our skeletal muscles. The active principle of the 

 suprarenal gland acts as a chemical whip on all such nervous 

 complexes. For example, the heart rate is accelerated and its 

 volume increased, the vasomotor tone is maintained, the reac- 



