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288 



DR. M. T. MASTERS ON THE MOBPUOLOGY, 



leaf-axils 



(1) median axil 



lateral axil sterile, (3) median sterile, (4) lateral fertile, and so 

 on. At the base of the branches the production of new shoots is 

 for some distance confined to the distal side, giving a curved 

 appearance to the shoot, the convexity being to the further, 

 the concavity to the nearer side of the shoot ; but towards the 

 middle, and thence onwards to the tip, the branchlets are given 

 off alternately to the right and to the left. Meehan * points out 

 " that in the most vigorous growths of Thuya gigantea and 1. oc- 

 cidenialis a branch appears at the eighth node, and always at the 

 eighth node when the vigour of the branch remains the same. 

 As the axis weakens, the branches appear at the sixth node. . . . 

 With greater weakness, the fourth node gives birth to the branch ; 

 and, finally, as the plant takes on its frondose flattened form, a 

 branch pushes from every alternate node. But in no case docs a 

 branch push at an odd number ; they are always from the second, 

 fourth, sixth, or eighth node." 



If for vigour, rapidity of growth on the leader-shoot be sub- 

 stituted, I concur with Mr. Meehan, as my observations tally 

 with his in the main, though there is no absolute rule in the 



matter : 



Mr 



: Biota orient alU has the branch-systems ascending and com- 

 pressed from side to side. The leaves are decussate, and branching 

 takes place from each of the lateral pairs, generally only from one 

 axil, the next succeeding branch being given off on the other side ; 

 rarely branches are given off from both sides. On the vigorous 

 leader-shoots, according to Meehan. branching takes place from 



















e^rery fourth node. 



In Chamcecyparis sphceroidea 9 referred by some authors to 

 Cupressus, and included, with Retinospora;* under Thuya by 

 Bentham and Hooker (Gen. Plant, iii. p. 427, 1880), the branch- 

 ing is peculiar, being umbellate or radiating, the main branch- 

 systems in this case not being in one plane, but partially from 

 the median as well as from the lateral leaves, and thus forming 

 inversely pyramidal or wedge-shaped branch-systems, resembling 

 the wedge-shaped tufts of leaves which occur at the ends of the 

 branches of some ot' the pines, e. g. Pin us ponder osa. The penul- 



branched 



some 





in the horizontal, others in the vertical plane. The leaves are 



Acad, Nat. Sc. Philadelphia, June 25, 1872, 



Meehan, in Proceedings 



33. 











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