156 



Witli emaiiatioii-beats ^) and with pulsation evoked by outside 

 radiations with polonium, there is often some increase of tonus, 



Fig. 3. 

 Frog's heart, Kronecker's cannula. 

 Deprived for some hours by potassium-free perfusion of diffusing potassium 

 and of part of the depot. Then pulsating during the night with 100 mgr. ofpotas- 

 sium-chlorid per litre. Next morning standstill with potassium-free Ringer's mixture. 

 Recovery of pulsation due to omnilateral polonium radiation. At the beginning of 

 the curve the polonium was taken away. 



Nearly half an hour later the polonium-beats cease. They had caused no increase 

 of tonus worth mentioning. 



which need not surprise us if we consider what has been stated sub a. 

 Increase of tonus, liowever, is not a tj^pical feature of alpha-auto- 

 inaticitj, since it can exist without this increase when it is brought 

 about from the outside by polonium-radiation. This is illustrated in 

 Fig. 3 "). A heart that after cautious, prolonged perfusion with pot- 

 assium-free Ringer's solution, had been deprived of a considerable 

 portion of its potassium depot, continued pulsating for a long time 

 also when subjected from the outside to omnilateral polonium-radi- 

 ation. These pulsations occur witliout additional increase of tonus. 

 The polonium is taken away at the beginning of the figure. 



Besides in the tonus-condition, the two automaticities are also 

 distinguished in the relation of the regularly pulsating hearts to the 

 action of the constant current, to the alternating current and to dia- 

 thermy. These distinctions have been desci-ibed by Dr. den Boer ^) in 

 his Thesis, so that I will not revert to them. 



1) Zwaardemaker and T. P. Feenstra, G. R. Soc. de biologie, t. 84, p. 377. 

 Paris 1921. Zwaardemaker, Klin. Wochenschr. Jahrg. I, N". 11. 1922. Arch, 

 intern, de Physiol, vol. 18, p. 284, 1921. 



2) Another instance is giten by Zwaardemaker and G. Grijns, Arch, néerland. de 

 physiol. t. 2, p. 502, 1918. 



3) M. den Boer, Dissertation. Utrecht 1 Maart 1921. 



