THE BEGINNINGS OF SPRING. 15 



this spot, one of the warmest and most forward hill 

 districts in the south of England, gives it an adventitious 

 value for every collector, and a real one for the student 

 of botanical history. Evidently, the hairy spurge grows 

 here, and only here, because, being a mountain species 

 of warmer climates, Claverton Down is the only hill in 

 Britain at once high enough and warm enough to suit it. 

 This explanation sufficiently accounts for its absence 

 elsewhere, but not quite for its presence here. How did 

 it get from the Continent to Claverton Down ? 



If the occurrence of the hairy spurge in England 

 were an isolated case, we might suppose that it had 

 been accidentally imported by man, or that the seed 

 had been blown here by the wind, or that it had been 

 carried over by clinging to the feet of birds. Such 

 accidents do undoubtedly account for many special facts 

 of distribution and acclimatisation for example, all 

 oceanic islands, as Mr. Wallace has amply shown, are 

 peopled with mere waifs and strays of various distant 

 faunas and floras in just this fragmentary fashion. But 

 the case of the spurge is by no means a solitary one ; 

 on the contrary, the south-western districts of England 

 and of Ireland are full of peculiar species found in no 

 other parts of Britain. Thus a pretty little purple 

 lobelia, a familiar plant in southern France and Spain, 

 is alone found with us on a single common near Ax- 

 minster in Devon. So, too, Cornwall and the Scilly 

 Isles are rich in southern forms. The arbutus, or straw- 

 berry tree, which grows so abundantly, with its white 

 bell-shaped blossoms and its pretty red berries, over the 

 Provengal hills, is met again quite unexpectedly on the 

 mountains of Kerry. The Mediterranean heath that 



