CHAPTER III. 



THE MORPHOLOGICAL COMPOSITION OF PLANTS, 

 CONTINUED. 



§ 187. That advanced composition arrived at in the 

 Arehegoniatw, is carried still further in the Flowering Plants. 

 In these most-elevated vegetal forms, aggregation of the third 

 order is always distinctly displayed; and aggregates of the 

 fourth, fifth, sixth, &c, orders are very common. 



Our inquiry into the morphology of these flowering plants, 

 may be advantageously commenced by studying the develop- 

 ment of simple leaves into compound leaves. It is easy to 

 trace the transition, as well as the conditions under which it 

 occurs; and tracing it will prepare us for understanding 

 how, and when, metamorphoses still greater in degree take 

 place. 



§ 188. If we examine a branch of the common bramble, 

 when in flower or afterwards, we shall not unfrequently find 

 a simple or undivided leaf, at the insertion of one of the 

 lateral flower-bearing axes, composing the terminal cluster 

 of flowers. Sometimes this leaf is partially lobed ; sometimes 

 cleft into three small leaflets. Lower down on the shoot, if 

 it be a lateral one, occur larger leaves, composed of three 

 leaflets; and in some of these, two of the leaflets may be 

 lobed more or less deeply. On the main stem the leaves, 

 usually still larger, will be found to have five leaflets. Sup- 

 posing the plant to be a well-grown one, it will furnish all 



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