122 DEVELOPMENT OF COMPOUND 



Locust (Gleditschia triacanthos) hang down with the coming 

 of the evening shades, and continue drooping through the 

 night ; but as soon as 



" Night's candles have burned out, and jocund day 

 Stands tiptoe on the misty mountain's top," 



they gradually elevate themselves to their usual horizontal 

 position. 



Another obvious distinction between stem ramification and 

 leaf ramification, lies in the fact that the branches and branch- 

 lets of a tree are all radially arranged or grow concentrically 

 about its stem, whilst the veins and veinlets of a leaf take 

 a symmetrical, bilateral arrangement on either side of its 

 costae or midrib, and develop in the same plane, or, more 

 correctly speaking, in a secies of closely approximated 

 planes. 



But in trees of a low order of organization, such as the 

 Coniferse, or cone-bearing family, to which the Pine, Fir, and 

 Larch belong, the main stem is well-defined, and the branches, 

 although disposed about it concentrically, are nevertheless 

 arranged symmetrically. The branches of the Pine and Fir, 

 for example, grow from their main trunk in verticils or 

 whorls, because they develop from the axils of closely-suc- 

 ceeding, spirally-arranged leaves, situated in the immediate 

 neighborhood of the terminal bud, from which the main 

 trunk proceeds each season. In consequence of the urging 

 of the formative power toward the top of each year's growth 

 of the leading axis, all its inferior lateral buds are suppressed, 

 and whorls of branches are produced with naked intervals of 

 stem between them. Now, if we imagine a vertical plane to 

 descend through the main axis or stem of one of these trees, 

 we will suppose it to be the Norway Spruce (Abies excelsd), 

 so as to divide the tree exactly from top to bottom, it is evi- 

 dent that this tree, like the body of man or of an animal, 

 would be divided into two perfectly symmetrical halves, 

 which joined together would make one complete symmetrical 

 whole. 



In addition to this, the branchlets which proceed from the 



