THE RANGE OF DOMINANCE 163 



original root system is present. The root of the plant, 

 like the basal end of the animal body, is the morpho- 

 logical expression of the performance of a certain func- 

 tional activity primarily subordinate to and dependent 

 upon the activities of other parts. Without the activi- 

 ties of parts representing higher levels in the primary 

 gradient, root formation does not occur, but when it has 

 occurred the products of the special metabolic activity 

 of roots transported to other parts affect the metabolic 

 processes there and so inhibit more or less effectively the 

 formation of roots there. 



From this point of view the apparent dominance of 

 the root system over other parts of the plant with respect 

 to root formation is not a feature of the primary and 

 fundamental relation of dominance and subordination 

 in the individual, but rather a secondary relation — trans- 

 portative rather than transmissive — unlike the primary 

 relation, and resulting from local differentiation which 

 is itself associated with and dependent upon the primary 

 relation. 



THE LOCALIZATION OF EXPERIMENTAL REPRODUCTION IN 

 RELATION TO DIFFERENT AXES 



It is often possible to alter the localization of the 

 new dominant region in the reconstitution of an isolated 

 piece by altering the gradient relations of the piece. A 

 few examples from the flatworm, Planaria, among 

 the animals and the liverwort, Marchantia, among the 

 plants will illustrate the point. 



It has been pointed out (pp. 80, 81) that the out- 

 growth of new tissue on a piece of Planaria isolated by 

 transverse planes of section is most rapid in the median 



