IQ6 INTERNAL SECRETION 



lating the sympathetic nerve fibres of certain organs. The in- 

 variable effect of adrenalin upon the sympathetic nerve fibres is 

 to intensify their activity, whether the nature of that activity be 

 stimulatory or inhibitory. 



With regard to the two last columns of the table, the follow- 

 ing facts must be borne in mind. The column before the last 

 shows the effects of ergotoxin upon the sympathetic system, while 

 the last column shows the effects of stimulation, by electricity and 

 by adrenalin, upon a sympathetic system which has been poisoned 

 by ergotoxin. Dale has shown that the toxic influence of pre- 

 parations of ergot, and especially of ergotoxin, produces a stimu- 

 lation, followed by inhibition, of the sympathetic nerve endings, 

 this toxic influence being solely confined to their function-pro- 

 moting activity, their function-retarding activity remaining un- 

 changed. An injection of adrenalin given under these conditions 

 produces, therefore, a paradoxical result. The conclusions to be 

 drawn from these phenomena will be discussed later. 



THE PHYSIOLOGICAL EFFECTS OF ADRENALIN 

 UPON THE SYMPATHETIC SYSTEM. 



The Vessels. The striking effect which the active principle 

 of the suprarenal has in producing contraction of the vessels, 

 naturally suggested the question : Is this result due to the direct 

 action of the substance upon the contractile elements of the 

 vessel walls ; or is it a secondary result, the outcome of the 

 stimulation of peripheral structures included in the sympathetic 

 system ? 



Oliver and Schafer at first assumed a direct action upon the 

 muscular tissue, and among the proofs which they advanced in 

 support of this theory was the effect produced by suprarenal 

 extract upon the heart and upon the striated muscles. 



Support is given to the theory of a direct action of the sub- 

 stance upon the vessel walls by the fact that, at a developmental 

 stage when nervous elements are not demonstrable in the vessel 

 walls, a distinct contraction of the vessels may be produced in the 

 embryo chick by the direct application of a drop of suprarenal 

 extract (Konigstein). 



By the artificial circulation of adrenalin through the hinder 

 extremities of dogs, I discovered that the contraction of the 

 vessels, which is shown by the decrease in the venous outflow, 

 will also take place if the animal is first paralysed by means of 

 large quantities of curarin, or if curarin has been previously added 

 to the blood circulating through the extremities. Tillie proved 

 that curarin produces paralysis of the vaso-constrictor nerve 

 terminals, and these experiments of mine go to show that the 

 effect of the substance in producing vaso-constriction is due, at 

 least in part, to a direct action upon the muscular structure. I 



