FROM SIMPLE LEAVES. , 127 



matous areola or interspaces between the fibres becoming 

 continually smaller as they approach their ultimate ramifica- 

 tions ; but where development is carried further, as in pinnate 

 and bipinnate forms, there is the same conical and attenuated 

 fibrous structure, and the same ultimate anastomosis of the 

 fibre when the developmental power of the leaflet has reached 

 its limit, just as in the simple leaf with the entire edge, where 

 the vegetative power of the fibre of the leaf is reduced to a 

 minimum, and the fibres, by consequence, anastomose among 

 themselves before they come to the margin of the leaf. 



The same laws of lateral or marginal leaf development 

 manifest themselves amongst leaves even when they are still 

 in a state of anastomosis, or only partially formed and sepa- 

 rated from each other. One, two, or even three generations 

 of partially-formed folioles may develop and remain associated 

 with each other, producing the bipinnated or tripinnated 

 forms, as is the case in the leaves of Ambrosia artemisicefolia, 

 or Koman Wormwood. And just as the branch is only the 

 tree itself on a smaller scale, representing a certain stage of 

 development through which the tree has already passed, and, 

 if severed from the stem and planted in the soil, would repre- 

 sent its exact condition during one period of its life, so a 

 careful comparison of the entire foliole with its collaterals, 

 proves that these collaterals are only incipient repetitions of 

 the entire foliole, and that they hold to it the same relation- 

 ship as the branchlets owe to the parent branch, and follow 

 the same law of retarded development and which is alike 

 visible in the rugged and gigantic branches of the lofty tree 

 which endures for centuries, despite the fiercest onsets of the 

 elements, and in the delicate fibrous ramifications of the leaf, 

 which a single night's frost can kill. Such is the grandeur 

 and simplicity of natural law. Correctly interpreted, we see 

 in the fibrous ramifications of the leaf a miniature or rather 

 model exemplification of those very natural laws which, ope- 

 rating on a more enlarged scale, build up the powerful 

 branches of the tree, with their innumerable branchlets. 



The accuracy of this reasoning will be rendered clear and 

 intelligible by Fig. 9, which represents a leaf of Kolreuteria 



