192 



The pulsations become smaller and less frequent, the mechanic exci- 

 tability slackens and disappears. 



This then is the fourth time that we find a contrast between 

 the condition produced by potassium-free circulation and the uranium 

 condition; recovery of pulsation through electritication with the one 

 and inhibition of the normal systoles with the other. 



In a previous paper ^) I demonstrated an antagonism between 

 potassium and uranium, viz. that the two elements compensate each 

 other's action when acting simultaneously in a circulating fluid. 

 This antagonism obtained for the heart, the vascular endothelium, 

 the curarised muscle '), the kidney '). As for the automaticity of 

 the heart radium-, respectively mesothorium-radiation (through glass 

 or mica) also appeared to be antagonistic to uranium. So it appears 

 after all that electricity in impulsive, sinusoidal periodical or continuous 

 form also counteracts uranium contained in a circulating fluid. 

 Electricity annihilates the favourable eflfect of uranium. On the other 

 hand electrification acts on the heart fed with a potassium-free 

 circulating fluid like potassium and like radiation. Potassium-radiation 

 with /3-rays (and y-rays) and prolonged electric stimulation in any 

 form appear, therefore, in many respects to act physiologically in 

 the same way. 



The physiological actions I have in mind are: 



A heart without circulation-potassium resumes its beats. 



1. with potassium '') 



2. with radiation, so far investigated only in a form in which 

 negative charges are given to the tissue "), 



3. with electrification. 



A normally beating uranium-heart is arrested : 



1. with potassium, 



2. with radiation ^), 



1) H. ZwAABDEMAKER. K. Akad. V. Wet. Arast. Proceedings 24. Fel. 1917. Vol. 

 25. p. 1096. 



2) I. GuNZBURG. Congress April 1917. The Hague. 



3) H. I. Hamburger (by word of mouth). Gf. also Hamburger and Beinkman. 

 K. Ak. Amst. Proc. 27 Jan. 1917, in which the substitution of potassium by 

 uranium was demonstrated with regard to the permeability of the kidney. 



*) Also with other radio-active elements. H. Zwaardemaker and T. P. Feenstra. 

 K. Akad. Amst. Proc. 30 Sept 1916, Vol. 25, p. 517. 



5) H. ZwAAEDEMAKER, C. E. BENJAMINS and T. P. Feenstra, Ned. Tijdsch. V. 

 Geneesk. 1916, II, p. 1923. 



6) H. Zwaardemaker, Congress. The Hague. April 1917. 



