GEOMETRICAL REPRESENTATION OF GROWTH. 41 



symmetry is almost immediately attained, may be regarded as a 

 transition from the loose aggregate of lateral members in more 

 simple plant-forms to the symmetrical condition demanded by a 

 radially symmetrical bulky axis. 



Now, whatever holds for lateral members of one cell only should 

 also hold for lateral members of cell-aggregates, and the principles 

 of symmetrical and asymmetrical growth in the production of cells 

 in Zone I. should apply equally well to the formation of emergences 



Fig. 18. — Root-apex of Aspidiv/m FiUx-Mas. 



based on these cells, which move over the paraboloid apex in the 

 same manner, but subsequently grow into more massive lateral 

 members, so that the same transition from a primitive spiral-vortex 

 construction to a symmetrical circular one should be traced in the 

 progressive specialization of phyllotaxis. 



In the same manner, lateral members would be formed: (1) 

 along paths of equal action ; (2) in a mechanical system, independ- 

 ently of any aim on the part of the plant, with a view to their 

 subsequent functions ; which (3) might require secondary alteration 



