262 GENETICS 



important in modern medical research that endocrin- 

 ology is now recognized as a very lusty infant in the 

 family of biological sciences. 



The chief endocrine structures in man are the thy- 

 roids, parathyroids, the two functionally and anatomi- 

 cally distinct lobes of the pituitary gland, pineal gland, 

 thymus, adrenal glands, portions of the pancreas 

 and the various sex glands (testes, prostate, ovaries, 

 etc.). These structures are physiological regulators 

 and have to do with the growth and development not 

 only of the body but also of the mind. Human in- 

 stincts, emotions, mental and psychic states are stimu- 

 lated, inhibited, altered and complicated by endocrine 

 action. The endocrines, therefore, constitute a large 

 part of the machinery through which heredity must act 

 to bring about its results and consequently it is possible 

 to control, to a considerable extent, the development 

 and behavior of man through the internal secretions 

 produced by these glands. "Some people are born with 

 so stable an endocrine relation," says Bandler, "that 

 nothing will alter the normal interaction of the endo- 

 crine glands ; others inherit or acquire endocrines so 

 unstable or deficient that nothing else can elevate them 

 to the threshold of the normal." 



9. THE RATE or DEVELOPMENT 



No doubt one essential feature in the development 

 of an organism is differentiation or the unequal assort- 

 ment of material as already mentioned in a preceding 

 paragraph, but another factor in somatogenesis is 



