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thence more sparingly into the alpine region. In this, their 

 distribution, like that of the boreal plants themselves, is regu- 

 lated by temperature ^ nature of soil, degree of exposure, and 

 such like, which exercise separately, and in combination, a very 

 marked influence thereon. For though not sufficient to account 

 for the existence of either of these types in their respective areas 

 (else why should the flora of the mountainous tracts of the south- 

 west of Ireland be of such an opposite character to that of Wales, 

 and the latter agree so closely with that of the Scottish High- 

 lands ?), yet, but for such influences, there seems no reason why 

 our lowland plants should not ascend to the summit of the 

 mountains, and our alpine plants descend to the plains* 



Such, then, is a general view of the geological relations of our 

 alpine flora — a subject, it may be, novel to some of you, but on 

 that account only all the more interesting. If the theory which 

 we have thus briefly stated, without entering into minute details, 

 be correct, and I do not see what valid objections can be taken to 

 it, then to the names of alpine, boreal, and highland, by which 

 this type of plants has been denoted, we may with great propriety 

 add another, and call it the Glacial Flora of Great Britain. 

 And whether you accept the theory or not, it at least has served 

 the purpose of turning your thoughts this fine summer evening 

 from the old petrified bones and shells hid in the bosom of 

 mother earth, to the robe of living verdure, she is now up on the 

 mountains, by alpine rock, and stream, and tarn, so joyously 

 wearing. And yet the latter speaks to us geologists as eloquently 

 and instructively, it may be, as the former, and tells us how, 

 in a phyto-geological point of view, the past and the present con- 

 ditions of our island are closely connected together. 



