104 ORGANIC STRUCTURE. 



membranes, each member being- impelled into definite 

 order and position according to the natural constitu- 

 tion of the plant ; we come now to describe the pro- 

 gressive growth of the second and third years, which 

 with figures of cross and perpendicular sections of 

 the stem in each year, will give as perfect an idea of 

 the constituents and their transformations as the 

 writer is able to convey. 



Trees are dormant in winter; throughout that 

 season no change whatever takes place in the dis- 

 position of the components of the stem. Every 

 member remains exactly as it was left at the time the 

 growth of the previous year ceased. On the approach 

 of the higher temperature of the spring, vegetable 

 life receives a new impulse, the buds burst their 

 hybernacla*, each shoot is elongated, leaves are 

 expanded, and, perhaps, flowers, and the embryo 

 fruit are displayed. The summer perfects all these, 

 the autumn again arrests the growth, the leaves drop, 

 and the whole plant returns again to its winter 

 repose. 



Such as have not produced their seed would, if 

 the summer were prolonged, continue to grow till 

 that purpose of their being took place ; but those 

 that have yielded fruit, or passed the period at which 

 it should have been produced, make a pause inde- 

 pendent of the heat of the season. The common 

 ash is an instance not only of late vegetation, but also 



* Winter covering. 



