THE INNERVATION OF THE HEART. 451 



show that diastole was the type of cardiac arrest that followed 

 total suprarenal inhibition due to overstimulation. Even digi- 

 talis will arrest the heart in diastole. 19 Arsenic, chloral, atro- 

 pine, the bromides, aconite, hyoscyamus, creosote, guaiacol, 

 antipyrin, acetanilid, iodoform are types of the active drugs 

 used in practice which, when administered in adequate doses, 

 do what the current does through the vagus: i.e., inhibit the 

 heart. Even quinine, one of the safest suprarenal stimulants, 

 is capable of causing heart inhibition. "The evidence is con- 

 clusive," says Wood, "that both in man and in the lower ani- 

 mals quinine in sufficient amount is a powerful depressant to 

 the heart-muscle and ganglia." 



"Both Schroff and Jerusalimsky noticed that the fall of 

 arterial pressure produced by quinine," continues Professor 

 Wood, "is preceded by a rise of pressure accompanied by an 

 increase of the cardiac action. This observation has been con- 

 firmed by G. See and Bochefontaine; but no observer seems 

 to have shown that the rise of pressure is more than a tem- 

 porary phenomenon." The kinship with vagal overstimulation 

 and the fact that it is but temporary are clearly defined in this 

 sentence. 



The parallelism between excessive vagal action and the 

 action of drugs on the adrenals is further exemplified in the 

 following sentence of Professor Foster's: "With a current of 

 even moderate intensity such a current, for instance, as would 

 produce a marked tetanus of a muscle-nerve preparation the 

 stand-still is complete, that is to say, a certain number of 

 beats are entirely dropped; but with a weak current the in- 

 hibition is partial only: the heart does not stand absolutely 

 still, but the beats are slowed, the intervals between them being 

 prolonged, or weakened only without much slowing, or both 

 slowed and weakened. Sometimes the slowing and sometimes 

 the weakening is the more conspicuous result." We have here, 

 again, the expression of the functional activity of both the 

 vagus and the suprarenal glands with fluctuations in their 

 individual supremacy. This is further illustrated by the fol- 

 lowing experimental data: "It sometimes happens," says Pro- 

 fessor Foster, "that, when in the frog the vagus is stimulated 



19 H. C. Wood: Loc. cit., 297. 



