HORMONES 175 



but here and there among the cells of the pancreas proper 

 are cells of a different type that are now known to manu- 

 facture a hormone which they pour out into the blood. 

 This hormone has to do with the utilization of fuel by the 

 muscles, and thus plays an important role in the func- 

 tional metabolism by which motion is produced. It is 

 found that when this hormone is deficient the ability of 

 the muscles to make use of sugar is seriously impaired. 

 Under ordinary circumstances, probably from eighty to 

 one hundred per cent of the fuel which the muscles burn 

 in making their movements is sugar. It is evident, then, 

 that an impairment of their ability to utilize sugar is a 

 serious matter. In the next chapter an account is given 

 of the disease known as diabetes, which results from defi- 

 ciency in the pancreatic hormone. 



Hormones Affecting both Basic and Functional 

 Metabolism. — Although for purposes of description a 

 fairly definite distinction has been drawn between the dif- 

 ferent kinds of metabolism, it is clear that they are more 

 or less closely inter-related, so that whatever affects one 

 can scarcely avoid affecting the other in some manner. 

 It would be expected that hormones which influence any 

 type of metabolism would bring about modifications in 

 other types as well. There is, however, at least one speci- 

 fic hormone which is known to exert a particular kind of 

 influence on basic metabolism and another influence on 

 definite kinds of functional metabolism. For this reason 

 it deserves special mention. 



> The Hormone of the Adrenals. — In close contact 

 with each kidney is a small glandular structure known 

 as the adrenal body. This body produces and pours out 

 into the blood a hormone to which various names have 

 been given, the most familiar of which is adrenalin. This 

 substance first came into prominence when it was discov- 

 ered that a little of it dropped on a wound would draw 

 together the edges of the injured blood-vessels and so 

 stop the bleeding. If a small quantity of the substance is 



