1878.] 



Alternate Stimulation of the Vagi. 



95 



nerve, even when the nerves were alternately stimnlated so as to 

 relieve one another. 



In 1875, Tarchanoff and Puelma* stated, " Si Ton excite longtemps 

 un des pnenmogastriqnes dn chien avec des courants forts jusqu'a 

 epuiser completement son action snr le ccenr, ce qni se manifeste par 

 le retonr de ses battements et si Ton passe immediatement a V excitation 

 de V autre, on n'obtient pins d'arret dn ccenr, et meme on n'observe au- 

 cnne alteration de son activite : et ponrtant le nerf excite en dernier 

 lien n'est alors, on le concoit, nnllement epnise." From this experi- 

 ment they concluded, " que chacnn des pnenmogastriqnes met en jen 

 tout l'appareil moderateur situe dans les parois dn ccenr ; et qu'nne 

 fois cet appareil epnise par I'excitation d'nn pnenmogastriqne, il ne 

 pent etre mis en activite par I'excitation de l'antre." 



In 1876, Tarchanofff published observations on the frog, in which 

 he states that the behaviour of the frog's heart to vagus-stimula- 

 tion is quite different, in respect of the mutual influence of the two 

 nerves, from the behaviour of the heart of dogs or rabbits: " J'ai 

 vn alors que si Ton attend pour exciter le second pneumogastrique 

 que le premier ait ete epnise par I'excitation, l'arret dn cceur s'obtient 

 de la facon la plus nette ; " and he concludes " Que chez les mammi- 

 feres les deux nerfs aboutissent a un appareil moderatenr commun, 

 tandis que chez la grenouille chaque nerf aboutit k un appareil inde- 

 pendant." 



Between the publication of Tarchanoff and Puelma's note and the 

 publication of Tarchanoff's later observations on the frog, the authors 

 of this paper undertook to check Tarchanoff and Puelma's statement 

 respecting mammals, and to extend the method of experiment to frogs. 

 In the case of mammals, dogs and rabbits were used. They were 

 rendered insensible by chloroform or ether, or subcutaneous injections 

 of hydrochlorate of morphia. Their vagi were exposed in the neck 

 and divided; and the peripheral ends loosely tied by ligatures. 

 Arrangements were made to rapidly shunt an induced, interrupted cur- 

 rent from a Dn Bois-Reymond's induction coil, from one vagus into the 

 other, the peripheral ends of the nerves being laid over fine platinum 

 electrodes for the purpose. In all the experiments save one a Daniell 

 cell was used to induce the currents. A cannula was placed in the 

 femoral artery (in one case in the carotid artery) and connected with 

 a kymograph, which wrote upon a moving sheet of paper. 



In the case of frogs, the brain, and sometimes the spinal cord, were 

 destroyed by pithing ; a stout glass rod was thrust down the gullet ; 



* Jean Tarchanoff et G\ Puelma, " Note sur l'effet de I'excitation alternative des 

 deux pneumogastriques sur l'arret du cceur." " Archives de Phjsiologie," serie II, 

 tome II, 1875. 



f M. de Tarchanoff, " Innervation de l'appareil moderateur du cceur chez la G-re- 

 nouille." Marey's " Physiologie Experimentale," II Annee, 1876, p. 289. 



