THE EFFECT OF RADIUM RADIATIONS ON 

 THE RATE OF CELL DIVISION 



CHARLES PACKARD 



From (he Zoological Laboratory, Columbia University 



The radiations of radium produce two distinct types of effects 

 on living matter, depending on the intensity of the radiation. 

 When the exposure is intense or prolonged many abnormalities 

 result. In the unfertihzed or freshly fertiUzed egg they produce 

 a marked cytolysis, in which the water holding power of proto- 

 plasm is markedly increased; with this condition is usually- 

 associated a derangement in the mechanism of mitosis. As a 

 result, the formation of polar bodies is interfered with or sup- 

 pressed, wholly or partially, or multipolar figures are produced. 

 The embryo is always abnormal in the case of Nereis and 4r- 

 bacia. Oscar Hertwig found that if the unfertilized frog egg 

 is radiated up to a certain point the resulting embryo after 

 insemination with normal sperm is abnormal, but if the radia- 

 tion is very intense development is haploid, the egg nucleus having 

 been rendered incapable of playing its usual part in fertihza- 

 tion. 



This phase of the subject has lead to no significant results 

 thus far, perhaps on account of the difficulty of interpreting 

 the very diverse effects. The disturbance of the chromatin 

 in division has lead Gunther Hertwig to draw interesting con- 

 clusions as to the functions of chromatin in heredity, but this 

 is aside from the general problem of the effect of radium. In his 

 experiments he employed radium as an effective means of injur- 

 ing the sperm, but his conclusions would probably have been 

 the same had he used any other means of disturbing the chromo- 

 tin without interfering seriously with the protoplasmic activi- 

 ties of the sperm. 



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