1002 



(2) a considerable proportion, but by no means all the species 

 of the grass-moors lower down; 



(3) a very small proportion of those species which have their 

 true home on the mountain-summits. 



It is possible thai the status of this transition formation may 

 be disputed, hence I have introduced it after dealing with the 

 Grimmia-heath, rather than after the grass-moor, so that being 

 acquainted with its allies at higher and lower levels, the nature of 

 the transition may be more evident. 



Now that all the natural formations have been examined, we 

 must once more emphasise, that the most gradual transitions exist 



Coast-cliff form. 



Ombrophile 

 Chomophyte form. 



Typical 

 Chomophyte form. 



Thermophile 

 Chomophyte form. 



Grass-slope form 



Grimmia-heath form. 



Transition form. 



4 



Alpine bog form. 



Hydrophyte form. 

 along watercourses 



Dune form. 



Sand-strand form. 



Hydrophj'te form 



Diagram of the relationsliip of the natural plant-formations. 



The connecting lines indicatc the relationship and to some extent the evolution, but no attention need be 



paid to the varying length of the lines, since these are determined merely by the space at our disposal, 



The arrows suggest the direction of development. 



