ECONOMY OF THE BODY 141 



part of the body, and carried by the blood to distant parts, 

 which it affects for the good of the organism as a whole." 



(3) The adrenalin produced by the medullary part of 

 the suprarenal bodies (situated in front of each of the 

 kidneys) is a very potent hormone, whose secretion is greatly 

 increased by strong emotion, e.g. of fear or rage. It brings 

 about a rapid increase in blood pressure, it affects the 

 distribution of the blood and the breathing movements, it 

 increases the excitability of the skeletal muscles and their 

 power of resisting fatigue, it increases the amount of sugar 

 in the blood and its coagulability. It is easy to see that 

 when the emotion of rage stimulates the flow of adrenalin, 

 it thereby prepares the body for a fight in a somewhat 

 detailed and very effective physiological fashion. Similarly, 

 the useful effect of adrenalin in contracting the tiny muscles 

 that erect the hairs of the skin is familiarly illustrated when 

 a frightened or at any rate excited cat increases its size in 

 facing up to a dog. Adrenalin is interesting in being the 

 only true hormone which has been made artificially ; yet 

 how far it is from being a simple substance is suggested by 

 its chemical name ortho-dioxyphenol-ethanol-methylamine, 

 which surely means some labour of synthesis whether in 

 the chemical laboratory or in the alchemy of the living cell. 



(4) Over-activity of the pituitary body, which projects 

 from the under surface of our brain into a well-protected 

 bony cup about the size of a small hazel-nut, leads to the 

 development of an unhealthy giant ; pituitary insufficiency 

 leads to an unhealthy dwarf, slow of pulse and weak in 

 energy. Both of these extremes are to be distinguished 

 entirely from healthy giants and dwarfs, who arise as freaks 

 or mutations. But besides regulating growth, the pituitary 

 body (especially in its posterior lobe) has to do with the 

 storage and mobilisation of carbohydrates. 



We see, then, the variety of the functions which hor- 

 mones discharge, and the impression would be heightened 

 if we considered those produced by certain parts of the wall 

 of the alimentary canal ; or that produced by peculiar islete 

 in the pancreas, which have to do with carbohydrats 



