602 LECTURE XXVI. 



Several names have been assigned to the substance, but that of adrenalin 

 seems most suitable. By fusing it with caustic potash, protocatechuic 

 acid is obtained. By the action of mineral acids, methylamine is split off. 

 Among the other cleavage-products, pyrrole, methyl indole, and pyridine 

 have also been observed. We are not much better informed concerning 

 the formation of adrenalin than we are concerning its constitution. We 

 do not know its source, although it is possibly derived from the proteins 

 and their disintegration products. 



As little as 0.0013 milligram of adrenalin will cause a noticeable increase 

 of the blood-pressure when introduced into the circulation. At the same 

 time it strengthens the heart-action. The peripheral vessels become 

 strongly contracted. Mucous membranes appear nearly white on account 

 of the almost complete absence of blood in them. Adrenalin also acts 

 upon the dilatator pupillce, retractor membrana nictitans, and the smooth 

 muscles of the eyelids. 1 These muscles contract when under its influence. 

 The movements of the stomach, the gall-bladder, and the urinary-bladder 

 on the other hand are possibly restricted. 2 



How shall we imagine that the suprarenal capsules act in the economy 

 of the animal organism? Evidently they are constantly giving up adrena- 

 lin to the blood either as adrenalin or perhaps in some kind of combination 

 such that all the organs innervated by the Sympatheticus are affected 

 by it. It is certainly interesting in this connection that neither their 

 development nor anatomical structure indicates that these capsules are 

 homogeneous organs. There are two distinct parts of the capsule, one of 

 which is derived from a collection of mesenchymatous cells in the vicinity 

 of the inferior vena cava and gives rise to the cortex, while the other origi- 

 nates from the abdominal sympathetic ganglia and forms the medulla. 

 There is considerable evidence which points to the fact that adrenalin is 

 produced by the cells of the medulla. We have, therefore, in a wide 

 sense an innervation process before us which is brought about by the aid 

 of a chemical product. It is certainly not without significance that the 

 Sympatheticus, or rather an organ derived from it, produces a substance 

 which acts upon it and the organs innervated by it. At present there is 

 nothing definitely known as to whether the sympathetic nerve influences 

 this internal secretion, but there is some evidence which indicates that 

 such is the case. 



We have already mentioned that there has been ascribed to the supra- 

 renal bodies an action in combating poisons. Although we do not doubt 

 in any way that these organs may have other functions than that of pro- 

 ducing an internal secretion, still there is nothing positively known as to 



1 M. Lewandowski: Zentr. Physiol. 12, 599 (1898). 



2 Boruttau: Pfliiger's Arch. 78, 97 (1899). 



