32 OP THE WOOD. 



ruptions in the formation of the wood from cold 

 or fickle seasons, and that in some trees the 

 thin intermediate layers, hardly discernible 

 in general, which unite to form the principal 

 or annual ones, may, from such fluctuation 

 of seasons, become more distinct than ii 

 natural to them. Such intermediate layers 

 are even found more numerous in some 

 trees of the same speeies and age than in 

 others. But as there is always a most mate- 

 rial difference between summer and winter, 

 so I believe will there always be a clear di- 

 stinction between the annual rings of such 

 trees as show them at all. Trees of hot 

 countries indeed, as Mahogany, and ever- 

 greens in general, have them but indistinctly 

 marked; yet even in these they are to be 

 seen. With regard to their greater com- 

 pactness on the north side of a tree, Du 

 Hamel justly explodes this idea. In fact, 

 there is most wood formed, and consequently 

 these circles are broadest, on the side most 

 favourable to vegetation, and where there 

 are most branches and leaves. This in a 

 solitary tree is generally towards the south; 

 but it is easy to perceive the occasional varia- 



