THE RANGE OF DOMINANCE 



157 



by inclosure in plaster of the distal part of the blade of 

 this leaf before its growth is completed is followed by the 

 development of a new leaf surface from each side of the 

 basal portion, as in Fig. 87. When the whole blade of 

 the leaf is cut off or inhibited, the margins of the petiole 

 just below the level of the cut give rise to a separate new 

 leaf on each side (Fig. 88). Here the basal portion of 

 the leaf and the distal region of the petiole margin 



Figs. 86-88, — Dominance and physiological isolation in leaf of 

 Cyclamen persicum: Fig. 86, intact seedling (from Hildebrand); Fig. 87, 

 development of new leaf blade from each side of leaf base after removal 

 of more apical portion; Fig. 88, development of new leaf from each side 

 of petiole margin after removal of whole leaf (from Goebel). 



evidently possess the capacity to develop as a leaf, but 

 are prevented from doing so as long as the original leaf 

 or its distal portion is present or active. 



Attention has been called to the fact that roots, 

 wherever they appear on the plant, are apparently 

 subordinate, specialized individuals and originate in 

 definite relations to parts which represent regions or 

 levels physiologically less remote than the root-tip 

 from a stem-tip or bud (see pp. 104, 105). Most plants 



