72 ON DIGITALIS, WITH SOME OBSERVATIONS ON THE UllINE. 



tate the distal cut end, tlie pulsations are slow, and the sarae 

 result takes place if we apply galvanism to the uncut vaguSj 

 and it is only natural to suppose that the poison circulating 

 over the heart's parietes might act either upon the terminal 

 branches of the nerve, or on the apparatus in the heart on 

 which these branches act, and through which they produce their 

 effect, just as upon the central end of the vagus, though prob- 

 ably with less force. The second part (b) of this theory I am 

 not inclined to accept, because M. Traube's experiments, I 

 think, prove that the action is altered in mammals by the divi- 

 sion of the vagi : and although Messrs. Dybkowsky and Pelikan 

 state that they have found the same results in mammals as 

 in frogs, they do not give definite details like M. Traube ; and I 

 am further hindered from accepting it, as in one of the two frogs 

 which I have been able to obtain, and which was poisoned 

 with woorari, its heart laid bare, and first a moderate, and then 

 an enormous dose of digitaline introduced under the skin, the 

 action was not so marked and distinct as Dybkowsky, Pelikan, 

 Fagge, and Stephenson describe it to be. 



The hypothesis that T have myself formed in regard to the 

 action of digitalis is as follows : — 



Digitalis causes contraction of the small arteries, and at the 

 same time acts on the regulating apparatus of the heart, both 

 directly, and to a much greater extent through the vagus, thus 

 causing slowing of the heart without loss of tension ; it stimu- 

 lates the musculo-motory apparatus, causing increased force of 

 the cardiac contractions. This primary stimulus then gives 

 place to paralysis — first partial, and then complete. The regu- 

 lating force gradually loses its power, so that the musculo- 

 motory power causes a quick beat to be occasionally interpolated, 

 ^s the regulating power gets enfeebled, it can only occasionally 

 assert its influence, and the pulse, formerly slow with occasional 

 •C|uick beats, is now a quick one, with occasional slow beats or 

 intermissions; as the regulating power becomes entirely lost, 

 the intermissions disappear, and the pulse becomes regular but 

 Tcry quick, the capillaries have also become paralysed and 

 •dilated, but occasionally, just before death, they become spas- 

 modically contracted. The musculo-motor power gets weakened, 



