698 



The veiitrifle-electfograms produced after the halving- of the ventricle- 

 rhjthm were compared in the first place with the electrograms 

 taken immediately before the halving, and at the same time with 

 all the previous!}' registered ventricle-electrogi-ams. 



2. A second series of experiments was made with frogs' hearts 

 in which, after the application of the mentioned poisons, halving of 

 the ventricle-rhythm had set in already. This halved ventricle-rhythm 

 was thereupon converted into the normal twice as quick one by 

 an induction-stimulus, as was mentioned in my previous essays ^). 

 The normal ventricle-rhythm was conxerted again into the halved 

 one. In this way I obtained in one photogram the ventricle-electro- 

 grams of the normal venti'icle-rhythm and those of the halved one. 

 During the normal ventricle-rhythm the impulse is transmitted 

 much slower thi-ough the ventricle than during the halved one, 

 because the number ot ventricle pulsations in the first rh\thnj is 

 twice as great as in the sec(>nd. Occasionally a spontaneous modifi- 

 cation of rhythm of the not-poisoned heart was registered. 



3. In a third series of expei'iments anticipated ventricle-systoles 

 were excited in the not-poisoned frog's heart by ai)])lying extra- 

 stimula to the auricle. I caused then in the beginning of the irritable 

 ventricle-period and at a later period anticipated ventricle-systoles. 

 As I explained already before, the electrograms of these anticipated 

 ventricle-systoles could be compared with those of the periodical 

 ventricle-systole^. The electograms of the anticipated ventricle-systoles 

 were also mutually compared. During the \ entricle-systoles that 

 were excited in the beginning of the ij-ritable ventricle period the 

 impulse was transmitted slower through the ventricle tha'n during 

 the ventricle-systoles that were excited at a later period of the irri- 

 table venfiicle-period. 



These 3 series of experiments produced me a rich material for 

 the study of the intluence of the velocity of intpnlse-transmission 

 on the shape of the ventricle-eleclrogram. 1 shall first discuss these 

 3 series of expei"iments successively, guided by some photograms, 

 and afterwards communicate my conclusions in a theoretical expla- 

 nation, and add to these conclusions a few consideration concern- 

 ing the signification of the views obtained for the electrophysiology 

 of the heart. 



I. Comparison of the ventricle-electro(jrain.'< of frogs' hearU before 

 and after the poisoning with digitalis. 



The experiments were made in the following manner. The frog 



. ^) Archives Néerlandaises de Ptiysiologie de I'hoinme et des animaux Tome I, 

 p. 271 et 502. 



