THE ADRENAL GLANDS 197 



the opinion that the anterior lobe or part of the gland affects 

 the growth of the skeleton and the posterior part causes several 

 important bodily changes. Although the hormone or hormones 

 of the posterior lobe have not been obtained in pure form, in- 

 jections of extracts from the lobe will cause a rise in blood 

 pressure, an active contraction of smooth muscles, and a con- 

 version of glycogen into sugar. Any irregularity in the gland 

 affects growth, especially that of the skeleton, and the tone of the 

 muscle cells of the blood vessels. Undersecretion in children 

 causes them to remain small and fat. Some dwarfs are known 

 U) have very small pituitary glands. These dwarfs are well-pro- 

 portioned, unlike the cretins with their overdeveloped heads and 

 abdomens. Too active a pituitary gland in a young person 

 causes an enlargement of the bones. The individual assumes 

 giantlike proportions. If the gland is affected in an older per- 

 son, acromegaly, a gradual enlargement of the bones of the 

 head, hands, and feet usually results. A rise in blood pressure 

 and the slowing of the heart beat usually accompanies the 

 condition. 



The adrenal glands. The adrenal glands (ad — on ; renes — 

 kidneys), called suprarenal bodies by some investigators, are two 

 small glands situated just above the kidneys. They weigh about 

 one seventh of an ounce. The inner part of the glands produces a 

 secretion called adrenin. The secretion, if there is any, of the 

 outer or cortical region has never been isolated and its function is 

 obscure. Adrenin, like thyroxin, can be obtained from the gland 

 in a pure form. It has also been built up or synthesized by chemists 

 in the laboratory. It is known commercially as adrenaline. Both 

 the natural and the synthetic product tend to contract the arteries, 

 thus causing an increase in blood pressure. Visceral arteries are 

 affected to a greater extent than the arteries leading to the muscles. 

 Adrenin also hastens blood clotting and strengthens the heart 

 beat. It stimulates the liver to release the stored sugar. This 



