f^v 



Parathyroids 



Thymus 



Adrenals 



Pineal body 



Pituitary, or 

 hypophysis 



Thyroid, or 



"shieldlike" 



gland 



Pancreas 



LOCATION OF ENDOCRINE GLANDS IN THE HUMAN BODY 



The glands of internal secretion produce substances that are distributed by the 

 blood and produce effects in remote parts of the body. Their names tell us nothing 

 about their functions. The name "hypophysis" means merely "under-body", from its 

 position under the brain. Adrenals are next-to-kidneys, while para-thyroids are 

 beside-thyroids. The names "thyroid" and "pineal" refer merely to shapes. The 

 pineal gland was supposed by Descartes to be the "seat of the soul" 



About a dozen hormones have been recognized. About half of these 

 have been obtained in a pure crystaUine form of a definite chemical com- 

 position. A few have been reproduced synthetically. Several of the en- 

 docrine organs produce more than one kind of hormone. The thyroid, like 

 the paired parathyroid, however, produces one particular kind of hormone 

 and nothing else, although each hormone may produce more than one kind 

 of effect. 



305 



