OF GROWTH IN TREES. 95 



have been made of new growths to the extremities of its 

 branches. These yearly vibrations of growth correspond 

 with the oscillations of the great pendulum of the universe, 

 and are faithfully recorded in the annual wood-rings visi- 

 ble on the cross-section, and in the bud-traces left on the 

 exterior bark of the young shoots and .branches. 



This however is not all ; for when we come to examine 

 carefully the different parts of the tree, when it is denuded 

 of its foliage, we find that each branch, and branchlet, and 

 shoot is characterized by its own peculiar fluctuation. In 

 the annual wave of growth which pervades each shoot, 

 there are three distinct stages which offer themselves for 

 consideration. Toward the bottom of each shoot, we have 

 formed a series of perfectly undeveloped internodes, which 

 support the covering-leaves, and which are visible after 

 their fall in a series of closely approximated annual scars, 

 called, in this work, bud-traces (gemma vestigia). Then 

 follow the partially developed internodes of the lower 

 leaves of the shoot, and then the principal internodes 

 which, through their expansion, form the shoot. But the 

 vitality of the leaves above the centre of the shoot becomes 

 more and more enfeebled, because they come to their per- 

 fection later in the season, when the heat and light of the 

 sun those stimulants of vegetable vitality decrease. 

 The internodes between the leaves consequently approach 

 each other, until finally we arrive at the terminal bud, 

 where the shoot again enters on the stage of rest. 



Now, as the cycle of accelerated and retarded growth 

 is repeated each season, and since there is always as 

 marked a contrast among the shoots as between the inter- 

 nodial developments of the commencing parts and those 

 that follow, the same wave of growth is perceptible amongst 

 the shoots ; and therefore we have marked out by Nature, 

 in a manner not less sure, the growth of the year, in cases 

 where the bud-traces are indistinct or wholly absent from 

 the axis of growth, as in the Buckthorn (Rhamnusfrangula). 

 In the Beech branch, represented on page 31, the wave of 

 growth appears to culminate about the centre of each 



