252 PROCESS OF DEVELOPEMENT. CHAP. IV, 



tion, rapid while it remains herbaceous, but slow in 

 proportion as it is converted into wood. Hence 

 moisture and shade are the most favourable to its 

 elongation, because they prevent or retard its in- 

 duration ; and hence the small cone of wood which 

 is formed during the first year of the plant's growth 

 increases no more after the approach of winter, 

 In length neither in height nor thickness. But the plant is 

 shoot, augmented in height by the addition of a new cone 

 protruded from the terminating bud in the succeed- 

 ing spring, that rises to a certain height above the 

 former cone, which it invests entirely with a new 

 layer of wood originating in the descending proper 

 juice, and augmenting the width of the trunk, and 

 is at last terminated by a bud which sends out a 

 new shoot in the spring following, and so on till the 

 tree ceases to vegetate ; so that at the end of a 

 hundred years the tree has been augmented in 

 length by a hundred longitudinal shoots, and at the 

 base by a hundred layers of wood, diminishing in 

 number as you ascend ; and yet the trunk is some- 

 times augmented in thickness by the addition of a 

 new layer, after the shoot has ceased to elongate.* 

 In thick- The trunk then is annually augmented in length 

 twk^he ty tne length of the terminating shoot; and in 

 annual diameter by twice the thickness of the layer. If the 

 induration of the trunk is effected slowly, then the 

 growth of the plant is rapid ; and if it is effected 

 rapidly, then the growth of the plant is slow, as in 



* Phys. des Arb. liv. iv. chap. iii. 

 3 



