THE CIRCULATION OP^ THE BLOOD 189 



treatment of diabetes, which is a disease that involves defective 

 oxidation of sugar. 



From little capsules that lie just above the kidneys the blood 

 absorbs a ferment that influences the muscles of the blood vessels, 

 and also has some effect on the nervous system. The amount of this 

 secretion is increased whenever strong feelings are aroused, such as 

 fear or anger. An increase in the amount in the blood acts upon 

 the liver, increasing the output of glycogen into the blood, and it 

 interferes with the secretions and contractions of the stomach. The 

 adrenin, as this substance is called, also hastens the clotting of blood. 



In young mammals there is a soft organ lying in the front part of 

 the chest, the t/iynms, the ferments from which have an important 

 influence on the growth of the animal. Another ferment that affects 

 the growth is absorbed by the blood from a little body lying at the 

 base of the brain, the pituitary. 



These various ferments are sometimes called internal secretions, 

 because they are absorbed from inside the organ, instead of coming 

 out of the gland through special ducts, as is the case with ordinary 

 glands. 



