A. C. REDFIELD AND E. M. BRIGHT 



45 



the rays increases the ratio between their physiological effect and their 

 ionizing power remains constant. 



It has been shown by Wilson that a number of slow /S-rays pro- 

 duce many more ions per cm. path through air than the same number 

 of fast ones. ^2 Since we have shown that there is a constant relation 



100 __ 



1000 



2000 



3000 



4000 



iOOO 



Fig. 6. The solid line represents the relative ionization, measured along the or- 

 dinate, produced by /3-rays of different velocities, measured along the abscissa. 

 The points represent the relative physiologically effective radiation in the same 

 beams, as determined with Nereis eggs. For data see Table II, experiment of 

 August 30, 1918. H variable. R = 7.65 cm. 



between the ionization produced in passing through the depth of 

 the ionization chamber and the physiological effect produced in pass- 

 ing through the Nereis eggs by a /3-ray of any velocity, it may be 

 concluded that in passing through a cell a number of slow /3-rays 

 will produce much more physiological effect than the same number 

 of fast /3-rays. 



