CHAPTER VI 



FIXITY OF POSITION AS A FACTOR IN THE 

 EVOLUTION OF PLANTS 



WHENEVER there is heavy weather on our coast 

 combined with unusually high tides the surf disturbs 

 the sand collected in the rocky inlets, and as likely as 

 not lays bare the roots of land-plants which straggle 

 down to the high- water level. Here as elsewhere the 

 vegetation of the land encroaches upon the shore 

 with some degree of regularity of zonation, so that it 

 may almost reach downwards during the quieter 

 seasons to the usual high-tide mark. After such a 

 favourable period, if a heavy sea comes breaking in 

 at the full of a spring tide the encroachment is apt to 

 be checked, the foremost of the advanced guard are 

 uprooted, and the roots of those that pressed behind 

 are exposed. A glance at the wreckage demonstrates 

 at once the extent and the intimacy of the attach- 

 ment of the ordinary land- vegetation to the soil. 

 It impresses more forcibly than any contemplation of 



B. 6 



