204 



ELEMENTS OF BIOLOGY 



velop as a mental and physical defective of a distinct type known as 

 a CRETIN. Defective thyroid in later life may result in various dis- 

 turbances, such as excess fat, nervous depression, weakness, and 

 impaired mentality. 



The Pituitary. The pituitary gland is situated in a depression 

 in the base of the skull, in Man almost directly above the posterior 



PfrurrARy body 



PAftATHrtiOIDS 

 THYMUS 



^ADdENALS 



MALE GONADS 



PINEAL BODY 



THYROID 



PANCREAS 



FEMALE GONADS 



Fig. 138. — Diagram to show the approximate levels in the human body at which 



are located the chief endocrine glands. 



portion of the roof of the mouth. It consists of two chief parts each 

 of which has a different hormonal function. The hormones from 

 the more anterior lobe of the gland appear to be important regu- 

 lators of the rate of growth; excessive or deficient activity of the 

 gland results in giantism or dwarfism. They also have to do with 

 the normal development and functioning of the reproductive or- 



