CHAPTER VII 



REGENERATION 



I. The action of the organism as a whole seems 

 nowhere more pronounced than in the phenomena of 

 regeneration, for it is the organism as a whole which 

 represses the phenomena of regeneration in its parts, 

 and it is the isolation of the part from the influence 

 of the whole which sets in action the process of regenera- 

 tion. The leaf of the Bermuda "life plant" — Bryo- 

 phyllum calycinum — behaves like any other leaf as long 

 as it is part of a healthy whole plant, while when isolated 

 it gives rise to new plants. The power of so doing was 

 possessed by the leaf while a part of the whole, and it 

 was the "whole" which suppressed the formative forces 

 in the leaf. When a piece is cut from the branch of a 

 willow it forms roots near the lower end and shoots at 

 the upper end, so that a tolerably presentable "whole" 

 is restored. How does the "whole" prevent the basal 

 end of the shoot from forming roots as long as it is part 

 of the plant? A certain fresh-water flatworm has the 

 mouth and pharynx in the middle of the body. When a 



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