198 DUCTLESS GLANDS 



sugar is then available for oxidation in the muscles. Thus the 

 muscles may receive an additional source of energy. The amount 

 of secretion from the adrenal glands is greatly increased during 

 strong emotional excitement such as fear and anger. If a person 

 is badly frightened, he seems to have unusual ability to escape 

 from the danger. This is due to the activity of the adrenals 

 which are stimulated by the emotion, and to the fact that adrenin 

 is absorbed into the blood stream in unusually large quantities. 

 The pouring out of the hormone by this gland increases the 

 blood pressure, strengthens the heart action, and contracts the 

 visceral arteries so that the blood supply to the muscles is in- 

 creased. At the same time, the liver is stimulated to release more 

 sugar than it would normally. In consequence, the blood supply 

 brings more food to the muscles which are better able to respond to 

 the emergency. Fatigue, too, is postponed. This often explains 

 the great strength people have during an emotional crisis. The 

 physical endurance of the dancing dervish is an example of adrenal 

 activity. If physical activity does not result from stimulation of 

 the adrenal gland, a violent nervous reaction takes place. People 

 should avoid, as far as possible, situations that will arouse 

 violent emotions, unless resulting activity is desirable. Since 



blood is withdrawn from the 

 viscera during violent emo- 

 tions, grave digestive disturb- 

 ances may follow. It has been 

 demonstrated that mental ac- 

 tivity may be seriously inter- 

 fered with, causing extreme 



Certain groups of cells, known as the islands of T1 ,, 7rm<an AQQ 

 Langerhans, are a part of the pancreas. They 



secrete insulin. Addlson s disease, charac- 



terized by great muscular weakness, darkening of the skin, low 

 blood pressure, feeble heart action, and intestinal disturbances, is 

 attributed, by many investigators, to degeneration or injury of 



