46 EFFECTS OF /3-RAYS OF DIFFERENT VELOCITIES 



The finding that the physiological action of the jS-rays is closely 

 related to its ionizing power is compatible with the view which has 

 been vaguely suggested by many investigators and definitely for- 

 mulated by Joly^^ and Richards and Woodward^^ that the physio- 

 logical effects of x-rays and radiations from radium are due primarily 

 to their ionizing effects upon substances in the protoplasm. It must 

 be remembered, however, that the relative ionization produced by 

 /3-rays is probably related to the relative absorption of these rays 

 by matter and our findings might be explained equally well in ac- 

 cordance with the principle of Grotthus. According to this view 



TABLE in. 



Averages of the Constants in the Fifth Column of Tables I and II Grouped according 

 to the Velocity of the fi-Rays Employed. 



slow |8-rays produce more physiological change than a corresponding 

 number of fast jS-rays because they are absorbed to a correspondingly 

 greater degree. Ionization of some of the constituents of protoplasm 

 need not necessarily be involved in the transformation of the energy 

 consumed in producing the physiological change. To establish the 

 fact that ionization of the cell constituents actually occurs under the 

 influence of these rays, quantitative data of another sort must be 

 forthcoming. 



^* Joly, J., Proc. Roy. Soc. London, Series B, 1914-15, Ixxxviii, 262. 

 ^* Richards, A., and Woodward, A. E., Am. J. Roent., 1917, iv, 564, 



