THE DEVELOPMENT OF COMMUNITIES 



307 



Fig. 153. — Lateral advance of the Rhacomitrium lanuginosum association upon basalt 

 rubble near Dienne, Auvergne, 1,100 m. {Photo by Uehlinger and Braun-Blanquet.) 



Fig. 154. — Centrifugal spreading and coalescence of plant cushions, Astragalus traga- 

 cantha on limestone rubble, Bonifacio, Corsica. {Photo by Hoffmann-Grobity.) 



