252 PLANT GROWTH SUBSTANCES 



little or no alteration in the callusing and budding behavior, while crown 

 gall tissues completely suppress budding for some distance and bring 

 about, per contra, an exuberant callus formation. Gautheret and Camus, 

 and de Ropp, claim that the new callus itself possesses tumor quaUties, 

 but this should be re-examined. 



From what I have said I think it is clear that the question of the role 

 of auxins in the vegetative development of tissue cultures has not yet 

 received the investigative attention that it deserves. Techniques for 

 such studies do exist, however, and it is to be hoped that they will be 

 utilized in the near future. 



