28 ANNUAL GROWTHS RECORDED 



and the brown scales which enveloped the young leaves fall 

 off, they leave ring-formed or annular scars at the bottom of 

 the shoot, and we recognize in these numerous girdles, the 

 place where, during the previous winter, the growing shoot 

 remained in a state of rest. These bud traces often con- 

 tinue visible for many years on the bark of trees, and 

 through this means we can ascertain the age of a branch 

 and the amount of its annual growth, as exactly as if we had 

 ourselves observed and marked its progressive growths from 

 year to year. The clearest marks of these bud traces may 

 be seen on the branches of the beech, the horse-chestnut, and 

 the maple, and are less visible on the bark of the birch, the 

 linden, and the fir, where they are not recognized through 

 the growth and changes of the bark. 



The distance between two sets of bud rings, estimated 

 from the under and upper limit of the rings, shows the 

 amount of shoot developed during the season ; and the age 

 of the shoot can therefore be estimated by counting the 

 number of sets of bud rings visible on its bark. 



So also the rate of growth of the shoot may be deduced. 

 It will be seen from the variation in the amount of shoot de- 

 veloped between the bud rings, that the growth of the 

 primary axis and its branches varies from year to year, and 

 that powerful growths are sometimes followed by growths 

 which are greatly retarded. Each branch has, in fact, its 

 own peculiar history of growth; and trees of different 

 species differ not more widely in this respect than two 

 branches on the same tree. 



But not only the fallen-off scales of the winter's bud, but 

 also the green leaves of the stem leave behind them a pecu- 

 liar scar on the bark, which marks the point of the stem to 

 which they were attached, and the number of leaf-scars be- 

 tween two bud-traces, therefore enables us to estimate cor- 

 rectly the number of leaves which were put forth during the 

 year, and thus we are able to picture to ourselves, not only 

 the amount of growth of the branches, but also the extent 

 to which the foliage was developed on them, and so, as it 

 were, to make the tree live again. 



