THE DUCTLESS GLANDS. 



403 



tracted from it in the pure condition, and which has the constitutional 



formula 



OH 



/\ 



| OH 



J 

 CH(OH).CH 2 .NH.CH, 



Adrenalin has also been prepared synthetically. 



The brown staining of the medulla when the gland is hardened in 

 a chromate solution is due to the combination of the chromate with 

 adrenalin, and the depth of the colour is roughly proportional to the 

 amount of adrenalin present. The accessory chromaffine material, which 



AAM\ U 



Adr. 



Vagi Intact 



FIG. 134. Blood-pressure tracing. Effect of injecting 0'05 mgr. adrenalin 



into a vein. 



Note the marked slowing of the heart. 



also stains with chromate, contains adrenalin. Adrenalin is completely 

 absent from the cortex of the suprarenal glands. 



When a small amount of adrenalin is injected into a blood-vessel 

 it produces constriction of almost all the arterioles of the body, and, if 

 the vagus nerves have been divided, an enormous rise of blood pressure 

 is produced (fig. 133). When the vagus nerves are intact the rise of 

 blood pressure is less (fig. 134). because, in accordance with Marey's 

 law (p. 223), slowing of the heart takes place. 



The action of adrenalin is not confined, however, to the blood- 

 vessels, but extends to every structure in the body which is normally 

 supplied with nerve fibres from the sympathetic system. It stimulates 

 the nerve endings of these fibres in the structures which they supply, 

 and the results of the injection of adrenalin are identical with those 

 of stimulation of the entire sympathetic system. Thus it increases 



