162 PLANT-LIFE ON LAND [CH. 



The contrary balance leads to restriction or even 

 to extinction. It is in this light that the vegetation 

 of the Golf-Links may be viewed. It may be taken 

 as an example of the occupation of a barren area 

 (Chapter VIII). The fresh blown sand from the beach 

 is a 7iidus presenting from time to time a fresh 

 surface, austere but ready to receive. Doubtless 

 there is a natural selection among the many germs 

 that fall upon it, and only those suited to the 

 situation obtain a permanent hold. Putting the 

 prime formers of the Dune on one side, the variety 

 of the species that bring about the conversion of 

 the Dunes from the White or shifting state to the 

 permanent condition of the Grey Dune is great. The 

 observation of it gives the opportunity for the study 

 of a new Flora in the making, aiid it may be noted 

 as we walk the Links, how many are the species 

 whose germs are called into existence, and how few 

 are physiologically chosen. 



In drawing this Series of Sketches to a close, 

 it must be clearly understood that no attempt has 

 been made to follow with exactitude the Evolutionary 

 History of Plants as we see them. What has been 

 attempted has been to illustrate along various lines 

 of thought, each suggested by common features of the 

 country, the outlook of Modern Botany. Each of 

 these lines converges in one way or another upon 

 the central problem of descent. The most prominent 



