4 6 



DISEASES OF CULTIVATED PLANTS 



free from each other. When the equilibrium of an organism 

 is upset there is often a tendency to revert in some of its 

 characters to an ancestral condition, and flattened or strap- 

 shaped fasciations are probably a reversion to an ancient type 

 of branching. When our higher flowering plants, from some 

 unknown cause, lose their balance, they revert to the long 



Fig. 6. of a cultivated carnation. Reduced. 



past branching conditions of Lycopods, Ferns, and Algae. In 

 these latter examples the branching is probably always 

 primarily in one plane. 



Congenital or ideal cohesion of parts is applied to those 

 structures where cohesion occurs before development. The 

 gamopetalous corolla is an illustration, having originated from 

 the congenital fusion of primitively tree petals, the free tips 



