44 BIOLOGY AND SOCIAL PROBLEMS 



in the higher animals, including man, a num- 

 ber of so-called ductless glands, such as the 

 thyroid gland, the pineal gland, the hypophy- 

 sis, the adrenal bodies, and so forth. These 

 have often been passed over as unimportant 

 functionless organs whose presence was to be 

 explained as an inheritance from some remote 

 ancestor. But such a conception is far from 

 correct. If the thyroids are removed from a 

 dog, death follows in from one to four weeks. 

 If the adrenal bodies are excised, the animal 

 dies in from two to three days. Such results 

 show beyond doubt that at least some of these 

 organs are of vital importance, and more re- 

 cent studies have demonstrated that most of 

 them produce substances which have all the 

 properties of hormones. A number of these 

 organs, like the thyroids, the adrenals, and 

 the sexual glands, have been studied from the 

 standpoint of their internal secretions and 

 have more than a passing biological interest. 

 The thyroid gland in man consists of two 

 moderately large lobes closely applied to either 

 side of the windpipe just below the larynx or 

 Adam's apple. As previously stated, the gland 

 is popularly known as the throat sweetbread 

 in contrast with the stomach sweetbread or 



