130 THE DIRECT INFLUENCE 



radium rays the egg and sperm-cells of carefully 

 pedigreed Onagra biennis at various periods of 

 their development, both before and during fertil- 

 ization. Plants grown from the seeds produced 

 under this influence varied profoundly from their 

 parents. Old characters disappeared, and new 

 ones became evident. The treatment followed 

 by heritable alterations was one in which the pol- 

 len grains were exposed for twenty-four hours to 

 rays from radium of 1,500,000 activity, con- 

 tained in a sealed glass tube. Thus only the 

 X-rays and possibly the more penetrating of the 

 Beta-rays were effective. The three individuals 

 with thick, leathery leaves, which resulted from 

 this treatment of the pollen, have already pro- 

 duced a second generation in which the new char- 

 acters are seen to be reproduced, and, while await- 

 ing the continuance of this work, it may be as- 

 sumed with fair certainty that the atypic strain 

 will continue its development parallel to the pa- 

 rental one. 



Other striking departures in ontogeny were 

 secured by exposure of the pollen and the ovary 

 before and after fertilization, and also by treat- 

 ment of maturing seeds, which were not transmis- 

 sible. Some slight modification of the technique 

 might well secure more extensive results and also 

 permit an analysis of the difference, if any, be- 

 tween somatogenic and oogenic inductions and 

 also illuminate the matter of the appearance of 

 bud-sports. 



