368 



PLANT SOCIOLOGY 



Syngenetically considered, the simple floating communities are 

 always the pioneers and do not reach beyond the pioneer stage. The 

 highly organized forest communities, in whose structure the most 



.&^A>r.--A; 









Smi^m^^'^:''^:iW 



\t':*" ^■■"- 





Fig. 179. 



-Interior of the liana-filled tropical rain forest on the Amazon River. 

 Huber, Arboretum Amazonicum.) 



{From 



varied types of communal life take part, are relatively stable end stages 

 of a very long-continued process of adaptation and selection. 



From these contrasting glimpses we discern what characteristics 

 are of use in judging sociological progression. The most important 

 are: 



1. The kind of union which holds the species and individuals together. The 

 closeness of the union is greatly influenced by the dependence of the constituents 



