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ISLAND LIFE 



PART II 



question of the means of dispersal; and where the 

 difficulties that present themselves are not how the species 

 reached the remote localities in which they are now found, 

 but rather why they have not established themselves in 

 many other stations which, so far as we can judge, seem 

 equally suitable to them. Yet it is a curious fact, that 

 the phenomena of distribution actually presented by this 

 group do not essentially differ from those presented by 

 the higher flowering plants which have apparently far 

 less diffusive power, as we have found in our discussion of 

 the floras of oceanic islands ; and we believe that the 

 explanation of this is, that the life of species, and especially 

 genera, is often so prolonged as to extend over whole 

 cycles of such terrestrial mutations as we have just 

 referred to; and that thus the majority of plants are 

 afforded means of dispersal which are usually sufficient to 

 carry them into all suitable localities on the globe. Hence 

 it follows that their actual existence in such localities 

 depends mainly upon vigour of constitution and adapta- 

 tion to conditions just as it does in the case of the lower 

 and more rapidly diffused groups, and only partially on 

 superior facilities for diffusion. This important principle 

 will be used further on to afford a solution of some of 

 the most difficult problems in the distribution of plant 

 life.i 



Concluding Remarks on the Peculiarities of the British 

 Fauna and Flora. — The facts, now I believe for the first 

 time brought together, respecting the peculiarities of the 

 British fauna and flora, are sufficient to show that there is 

 considerable scope for the study of geographical distribu- 

 tion even in so apparently unpromising a field as one of 

 the most recent of continental islands. Looking at the 

 general bearing of these facts, they prove, that the idea so 

 generally entertained as to the biological identity of the 



1 Mr. W. H. Beeby informs me that in the Shetland Isles, where he has 

 collected for five summers he has found several plants new to the British 

 flora, and a few altogether undescribed. Among these latter is the very 

 distinct species of Hieracium {H. Zetlandicum), which is quite unknown 

 in Scandinavia, and is almost certainly peculiar to the British Islands. 

 Here we have another proof that entirely new species are still to be dis- 

 covered in the remoter portions of our country. 



