THE EFFECTS OF THE BETA AND GAMMA RAYS OF 

 RADIUM ON PROTOPLASM 



CHARLES PACKARD 



From the Zoological Laboratory, Columbia University 



TWENTY-FIVE FIGURES (THREE PLATES) 



The present investigation has been carried on for the purpose 

 of determining the effects of the beta and gamma rays of radium 

 on protoplasm. Much work has been done during the last ten 

 years on the general effects of the radiations, but the results 

 have been conflicting, and the opinions as to their meaning far 

 from unanimous. Conflicting results are found to occur for 

 two reasons ; first, because different types of * cells react very 

 differently to the same stimulus; and second, because very 

 different methods of applying the stimulus have been employed 

 on the same kinds of cells. The first point calls for further 

 inquiry as to why cells differ from each other in their ability to 

 absorb the rays emitted by radium; the second, for a more care- 

 ful analysis of the action of the different kinds of rays. This 

 paper deals with the second point. 



The three types of radiations given off by radium differ 

 markedly from each other in their physical properties. 



The alpha rays, which are chemically the most active, possess 

 so slight a power of penetration that they do not reach the 

 object of study, being entirely absorbed by the glass tube in 

 which the radium salt is held. They may therefore be left out 

 of this discussion. 



The beta rays consist of negatively charged particles which 

 can be deflected in a strong magnetic field. The rays are not 

 homogeneous but are made up of particles whose speed varies 

 from 0.3 to 0.99 of the velocity of light. The slower particles 

 are deviated more sharply in the magnetic field than are the 

 high speed particles and are much more readily absorbed by 



323 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 19, NO. 3 



