78 



BRITISH FOREST TREES. 



the space of country covered by its shade is extend- 

 ing with a rapidity unparalleled in the history of any 

 other ligneous plant. 



Larch is generally conceived to be an alpine * plant, 

 and its decay in the low country attributed to situa- 

 tion or climate. This idea seems to have arisen from 

 its locality in Italy, and from observing it succeed so 

 well in our alpine districts, not taking into account 

 that the soil is different, — that it may be the soil of 

 these districts which conduces to the prosperity of 

 the larch, and not the 4atitu^. Throughout Scot- 

 land, wherever we have observed the decay, it appear- 

 ed to have resulted almost solely from un suitableness 

 of soil. We have witnessed it as much diseased on 

 our highest trap hills, 1000 feet in altitude, as on a 

 similar soil at the base. Yet the freeness from pu- 

 trescency or miasma of the pure air of the mountain, 



* There is yet no sufficient data for the term alpine plant, but 

 with reference to latitude. The influence on vegetables, arising 

 from rarefaction and diminution of pressure of atmosphere, from 

 difference of stimulus of solar ray — when the entire ray of light, 

 heat, and chemical power, though less intense, is radiated fresh, 

 and not much broken or modified by refraction and reflection, and 

 heat communicated more in proportion by radiation than by contact 

 of heated air ; or from difference of electric or galvanic or other 

 meteoric impression connected with altitude or ranges of moun- 

 tains, or with primary rocks or more upright strata, has not been 

 made the subject of research, at least has not been sufficiently in- 

 vestigated by any naturalist. 



