778 



caesium- and radium-pulsations have been registered, every time 

 w^ith an interval of equilibria without pulsations. 



The second curve originates from another experiment. The registering 

 leaf moved along at the rate of i cm. per minute. The piece cut 

 from the graph relates to a caesium-standstill after radium, succeeded 

 by caesium beats. The transitions in either case, illustrated here, 

 took place per crisin. 



Conclusions 



1. The light radio-active metals and the allied caesium, as well 

 as the heavy radio-active metals uranium, thorium, niton and radium, 

 sustain the contractility of the isolated frog's heart (ventricle pulsating 

 on its ov^^n automaticitj-). 



Effectual doses for summer frogs are: 

 of potassiumchloride from 30 to 50 mgr. per L. (min. 20 — 25 mgr.) 



" rubidiumchloride from 40 to 80 „ „ ,, ( „ d= 30 ,, ) 



" caesiumchloride from 40 to 80 ,, ,, „ ( „ =fc 30 „ ) 



" uranylnitrate or acetate from 1 to 6 ,, ,, ,, ( ,, =fc 0,7 ,, ) 



" thoriumnitrate from 2 to 10 ,, ,, „ 



" emanation less than 100 Mache-units 



" radiumsalt less than 3 millionths of a mgr. per Liter. 



2, A biological antagonism exists between : 



I Potassium \ , Uranium 



^Thorium 



Rubidium , „ . , 



i emanation I 



Caesium • J [Radium 



3. in all probability caesium emits /?-rays of very low penetrating 



power, upon which depends its similar effect to that of potassium 



and rubidium. 



