ENDOCRINE THERAPEUTICS 



the word hormone, the literal meaning of which is 

 something that excites. Schafer, appreciating 

 the fact that some hormones inhibit, invented a 

 new word, chalone, for these ; he groups hormones 

 and chalones together as autacoid substances, 

 because of their drug-like action. Quoting from 

 Bainbridge's Essentials of Physiology : " In such 

 a community it is clearly of the utmost importance 

 that the various groups should work in harmony, 

 and, to ensure this, they must be linked up by 

 some controlling mechanism. Two such mechan- 

 isms are found in the body, (i) a system of chemical 

 messengers or hormones, and (2) the nervous 

 system. The former is the more primitive of the 

 two methods. A hormone is produced in one 

 organ and is carried to another, exciting or 

 restraining its activity. For example, as the acid 

 contents of the stomach pass into the bowel, they 

 lead to the production of a hormone in the 

 intestinal wall. The newly formed substance 

 is taken up by the blood and carried to the 

 pancreas, which it stimulates to secrete the 

 juice required for the next stage of the digestive 

 process. Such a method of communication is 

 comparatively slow, and where rapidity of trans- 

 mission is important the messages are conveyed 

 by the nervous system." 



