Regeneration 257 



particularly light and physiologically active substances. There is still op- 

 portunity for fruitful investigation through an experimental manipulation 

 of the developmental process itself, especially by work on problems of 

 regeneration such as have been discussed in this chapter. The significant 

 results of earlier botanical workers in this field, now cultivated somewhat 

 less actively than in the past, could be extended very profitably by sup- 

 plementing the older methods with the advantages of modern techniques. 



