THE ANATOMY OF THE ROOT 



55 



be operative in any given case. The individual differences which 

 exist in plants with respect to their capacity to respond to stimulus 

 in the production of adventitious structures undoubtedly lie deeper 

 than the matter of tissue relations, and may be hereditary. 



The importance of the potentiality in economic plants to pro- 

 duce adventitious roots and shoots can hardly be overestimated. 





~>A ■- 









'<''<X f ~A, 



^^ ' h^.^ 



Fig. 11. The origin of an adventitious root in Zea. 



Investigations by Robbins and coworkers (lo, ii), Cooper (x), 

 Zimmerman and Wilcoxon (15), Bonner (i), and many others of 

 methods of artificial stimulation in the production of adventitious 

 roots through the use of phytohormones and other growth-stimu- 

 lating substances have been productive of most encouraging results. 



LITERATURE CITED 



I. Bonner, J., "Vitamin Bi: A growth factor for higher plants." Science 8j: 



183-184, 1937. 

 X. Cooper, W. C, "Hormones in relation to root formation on stem cuttings." 



Plant Phys. 10: 789-794,1935. 



3. Crooks, D. M., "Histological and regenerative studies on the flax seedling." 



Bot. Gaz- 95- -LOS-XT,^, 1933. 



4. Hansen, A., "Vergleichende Untersuchungen iiber Adventivbildungen bei 



den Pflanzen." Abhandl. Senckenberg. Nat. Gesell. 12: (i47)-i98, 1881. 



