777 



opposite to that of the lutoji-atoms. Rutherford ') has also observed 

 that probablj potassium emits few but highly penetrable /^-rajs, 

 in contradistinction to the more numerous but less penetrating ones 

 of rubidium. One is thus led to suppose caesium to throw out still 

 more numerous, but extreujely absorbable /i-rajs. This is why in 

 the circulating fluids the required caesium-dosis and the rubidium- 

 dosis are about equal, and on the other hand why this radiation has 

 not yet been demonstrated physically. On\y the atoms from a caesium- 

 preparation, lying very near the surface, will be capable of exerting 

 any effect. (Chemical? or ionising?). 



The emanation-experiment naturally led ns to investigate with a 

 radium-solution. Owing to their being completely absorbed the «-rays 

 of radium exert an enormous effect in the immediate pioximity. 

 That is why only few are required to obtain the restoring effect 

 upon the perfused frog's heart: 3 microgr. of radium per liter of 

 circulating fluid will do. So, if this oligodynamic radium-dosis (or 

 double this dosis) is rapidly sent through the lacunae of a frog's 

 heart that pulsates with 80 mgrms of caesium-chloride, a standstill 

 will commence after a short wait, just as with emanation. Afterwards 

 rhythmical beats will reappear, ttiis time — after the caesium has 

 been extruded — in consequence of the radium-action. By allowing 

 caesium to flow through again at this moment w^e again succeeded 

 in evoking a fresh standstill and — after extrusion of the radium — 

 finally again vigorous caesium-beats. 



The subjoined figures illustrate the phenomenon. Fig. 2 shows the 

 arrest of caesium-beats by radium, and the subsequent recurrence 

 of normal radium-pulsation after the standstill, when the caesium in 

 the heart is completely substituted by radium. 1 cm. of the abscissa 

 corresponds with the time of 1 minute. The curve is taken from a 

 continuous graph, in which by interchanging the feeding flasks, 



Fifi:. 2. 



Fig. 3. 



1) Rutherford in Marx's Hdb. der Radiologie, Vol. 2, S. 530. 



