STRUCTURE.] ANOMALOUS STRUCTURE CALYCANTHS. 209 



the lateral branches, where the afflux of the sap is diminished, 

 and the longitudinal growth consequently reduced to the low- 

 est possible degree, as, for instance, in the Larch, Cedar, 

 Salisburia, &c. These stunted lateral branches, which are 

 for the most part also fructiferous, present the greatest ana- 

 logy in their formation with the stems of the Cycads." (Ray 

 Papers, 1846, p. 21.) 



To the characters above assigned to the stem of woody 

 Exogenous plants there are some remarkable exceptions, 

 caused by anomalous growth, and arising from a breaking up 

 of the woody zones, or their fusion, or their separation by 

 layers of cellular matter, or by the constant extension of 

 their stem into angles, or by the formation in the same stem 

 of several centres of growth instead of one. In all these 

 cases it is interesting to observe that the first growth is 

 normal, however anomalous it may afterwards become. 



Mirbel has noticed the unusual structure of Calycanthus 

 (Annales des Sciences, vol. xiv.), in the bark of which, at 

 equal distances, are found four minute extremely excentrical 

 woody axes, the principal diameter of which is inwards ; that 

 is to say, next the wood. The existence of this structure, 

 noticed by the discoverer only in C. floridus, I have since 

 ascertained in all the other species, and also in Chimon- 

 anthus. Gaudichaud attempts to explain this curious mode 

 of growth upon the supposition that each leaf forms three 

 fascicles of woody matter, whereof the central is the most 

 powerful, and produces the mass of the stem ; and the lateral 

 ones, which are much weaker, give origin to the accessory 

 axes ; and he states, that in climbing' Sapindaceous plants 

 the same phenomenon occurs, only to a far greater extent. 

 He represents that in those cases the fibres of each leafstalk 

 separate into three or four principal branches, each of which 

 applies itself to one of the internal woody axes of the stem, 

 which, in time, consists of from four to eight distinct axes, 

 the central being larger than the others, and each having its 

 own cortical integument. The fact is curious, (Arch, de 

 Bot., ii. 492.), and has been confirmed by Treviranus (Ann, 

 of Nat. History, N. S. i. 126). 



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