lU THE CONTROL OF LIFE 



so that there may be no disunion in the body, but 

 that the various members should have a common con- 

 cern for one another " (1 Cor. xii. ; Moifatt's Transla- 

 tion). 



Discoveries, still in rapid progress, in regard to certain 

 apparently ' inferior parts,' the organs of internal 

 secretion, have profoundly changed our whole scientific 

 picture of the internal economy of the body. A few 

 illustrations must be given. 



One of the most important digestive organs in the 

 body is the pancreas or stomach-sweetbread. It pours 

 into the beginning of the intestine a large quantity of 

 digestive ferments, which attack all the different kinds 

 of food — the starchy, the fatty, and the proteid. For 

 a long time it has been known that this secretion of 

 ferments was most copious after meals, and this was 

 usually attributed to orders coming through the nervous 

 system, commanding the pancreas to secrete abundantly 

 at the appropriate time. But Professors Bayliss and 

 Starling showed (about 1905) that a substance called 

 secretin is made by cells in the wall of the intestine under 

 certain conditions of food, is carried away hy the blood, 

 and on reaching the pancreas provokes secretion. The 

 secretin is a specific messenger, carried by the blood, 

 which provokes an answer when it reaches the appro- 

 priate place. Such chemical messengers or internal 

 secretions were called by Professor Starling " hor- 

 mones." 



The thyroid gland near Adam's apple furnishes to 

 the blood an internal secretion which is essential to 



