202 SPRING. 



lateral twigs should be cut off, the new wood over them 

 heals up, and they totally disappear, so that a pine, 

 when it gets old, is very unlike the young tree. There 

 is also a strangulation of the lower branches, by means of 

 which they are thrown off in a dead state ; for in those 

 vast forests of nature's planting, to which man never 

 applied a pruning knife, the bark is often found without 

 any perforation or irregularity, for a length of forty, 

 fifty, or sixty feet. We cannot exactly know what 

 may go on in the internal part of a tree ; but there are 

 some circumstances that would lead us to suppose that 

 the wood of a tree has the power of assimilating those 

 parts of branches that are inclosed in it. We know 

 that in those trees that are under consideration, the 

 lengthening takes place only at the extremities ; we 

 know, also, that the annual additions are longest 

 about the middle time of the growth, and that they are 

 short in the infancy and old age of the tree ; but in- 

 stead of finding the root cut of a pine knotty, we find 

 that, if it has grown in a close forest, it is without any 

 knots at all, or any node or enlargement of the pith 

 that could lead to the supposition that there ever had 

 been any branch there. In respect of their elongation, 

 all branched trees are nearly alike, and this would lead 

 to the supposition that there is an internal power of 

 absorption in them all, by which the parts of the 

 branches that are enveloped in the wood are obliterated. 

 The limits as to size of branch to which this is con- 

 fined, are very imperfectly known ; and it is doubtful 

 whether it takes place in branches that are pruned 

 artificially. 



When it was stated that the stems of branched trees 



