44 EFFECTS OF jS-RAYS OF DIFFERENT VELOCITIES 



given. The units in which these values are expressed are arbitrarily- 

 chosen so that if a direct relation exists between the abihty of /3-rays 

 of any velocity to act upon living cells and to ionize air the figures 

 in this column will approach a constant with a value about 1 .0. This 

 is seen to be the case. Individual figures fluctuate considerably from 

 this value, as is to be expected in constants derived from physio- 



HR 1000 2000 3000 4000 5000 6000 



Fig. 5. The solid line represents the relative ionization, measured along the 

 ordinate, 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 I, experiment of 

 July 9, 1918. H = 477 gauss. R variable. 



logical data, but the deviations do not show any correlation with the 

 velocity of the jS-rays under consideration. We have collected all the 

 constants from Tables I and II into groups according to the velocity 

 of the |8-rays and have presented the average for each group in Table 

 III. When this is done the fluctuations in the individual constants 

 balance out and it becomes clearly apparent that as the velocity of 



