MAESHES APPEAEING IN POKESTS. 81 



same time, another erplanation of the cause of the phenomena 

 suggested itself to me when the details were given, namely : that 

 before the rising ground was planted much of the moisture falling as 

 rain upon the upper part of it spread under the surface, being pre- 

 vented by rock or clay from sinking, and oozed out at the lower level; 

 but after the plantation was formed less of the rain-fall reached this 

 impervious layer. 



But in either case all may be accounted for without prejudice to 

 the doctrine now under consideration. The planting of the trees was 

 followed by the desiccation of the swamp ; the destruction of the 

 trees, by its restoration. 



Sect. II. — On the Occasional Appearance of Marshes on the 

 Destruction of Forests. 



In the case of the disappearance of a swamp on the planting of an 

 adjacent rising ground with trees, and the reappearance of the swamp 

 on the destruction of the trees, the one phenomenon may be con- 

 Mdered the counterpart to the other, and both of them in accordance 

 with the exposition which has been given of the absorption of moisture 

 from the soil by the roots, and its emission into the atmosphere by 

 the leaves. Other cases of the destruction of woods having been 

 followed by the appearance of swamps have been brought under 

 my notice. 



In Eussia, some years ago, in the course of conversation on the state 

 of the forests with an intelligent lady, the niece of a forest official, I 

 learned that there, as elsewhere, when ground is cleared of firs and 

 pines, as it often is by extensive fire^, it often happens, so often that 

 in some districts it may be said that generally, there spring up birches 

 in great abundance ; and, she added, that in some cases the clearing 

 away of a wood converts the ground on which it grew into a morass, 

 which, when it is replanted, is commonly replanted with willows. 



I accept the statement as made. I pass at present the growth of 

 birches where previously grew the pine and the fir, but with the 

 intention of reverting to it afterwards. I call attention to the morass, 

 and suggest the encjuiry, How came it to pass that there was no 

 morass there before ? 



I consider there was none before, most probably because all the 

 water which went to the subsequent creation and maintenance of the 

 morass which subsequently appeared was raised by the trees and 

 passed into the atmosphere, in accordance with what has been 



