234 



liad cxistcnl for altoul one miiinlo, liaUiiig oF i'liytlnn ücoiin-ed. In 

 this lialved rlivthin llie lieai'l coiitiiiiied tu pulsate tbr more tlian 

 2'/, niiimtes, after wliieli tlie usual rli^tliin returned, in the i»egiiining 

 with systoles of equal height. After this slov/ rhythm the height of 

 the systoles gradually decreases. The preceding slow rhythm had 

 contributed to make the first systoles higher. Tlie first systole of 

 Fig. 2 is liie 15«'' after the halved stage. The systoles continue here 

 to decrease in height. From the G'*" systole in this figure the alter- 

 nation is distinctly extant. We see now the little systole constantly 

 diminish in height, till the rhythm halves again. I hope to give an 

 explanation of this fact at the end. Conducted by this observation 

 which I made several times myself, from which appeared, that 

 alternation occurs as a transition from the normal rhythm into the 

 halved one, and conducted by the well known clinical observation 

 that p. alternation occurs especially with paroxysmal tachyeardies, 

 1 have tried to produce heart-alternation in my frogs in a simple 

 way. The result answered entirely to my expectations. I suspended 

 in the usual way an extirpated frog's heart, and raised then the 

 temperature of the sinus veiiosus by making a hot RingersoUition 

 trickle on it. 



My intention was to make the impulsions proceed from the sinus 

 venosus to the ventricle in a quicker tempo, whilst the temperature 

 of the ventricle remained the .same. As I expected the ventricle 

 began indeed to ]ndsate in alternation. Fig. 3 (at V. sinus venosus 

 ealefied). In this way 1 could cause nearly every extirpated frog's 

 heart to pulsate alternatingly. Thus 1 suspended e.g. 28 March 

 10 frog's hearts and found with 9 of these alternation after calefaction 

 of the sinus venosus, with the 10''' polygeminy occurred. (Every 4 

 to 8 systoles 1 ventricle-systole fell out here). Refrigeration of the 

 sinus venosus was then again sufficient to change the alternation 

 again into the normal rhythm. (Fig. 4 at A sin. venosus refrigerated). 



Alternation as transition between the normal and the halved rhythm 

 occurred hereby likewise frequentl3^ 



So we see in Fig. 5 upper row at V, on account of calefaction 

 of the sinus venosus, alternation appear which disappears again at 

 A in consequence of i-efrigeration. In the lower row occur a few 

 curves of another heart in the halved rhythm between the alternation- 

 pulsations (at V the sin. venosus is here likewise calefied, at A 

 refrigerated). 



Sometimes 1 obtained in this experiment for a short time heart- 

 alternation, but often also the heart continued to pulsate for a long 

 time in alternation. It makes the impression that the average normal 



