122 Prufussoi' iJicksoii on tlic Sqjta acrons lli.c iJitds 



vascular Ituiidles arc scattered, very imicli as in a 

 monocotyledon. The diameter of the stem is increased, 

 from year to year, by the formation of secondary 

 bundles, with intervening smaller-celled parenchyma, out 

 of a persistent meristem, or extra-fascicular cambium, 

 beneath tlie rind, somewhat as in the monocotyledonous 

 Dracmna. On the inner side of the rind, just outside this 

 meristem, long fibres, resembling bast fibres, occur, singly 

 or in bundles of two or three together. It will thus be seen 

 that in the rind, here, the appearance of ordinary dicotyle- 

 donous structure is curiously simulated. The cambium- 

 like meristem and the bast-like fibres in Bougainvillea, 

 however, are both cxtra-fascicular. In the fibro-vascular 

 bundles the dotted ducts are of peculiar character. They 

 are formed from comparatively short cells applied to each 

 other by horizontal extremities. Most of the horizontal 

 septa between the component cells become perforated in 

 the ordinary way by the formation of a large round hole ; 

 but a certain number — say one in six or seven — of the septa 

 persist as diaphragms, which exhibit thickening in the 

 form of a very beautiful hexagonal reticulation. The spaces 

 of the mesh-w^ork are not perforated, but are closed by a 

 thin membrane. 



Tcstudinaria clcphantiins. — The fibro-vascular bundles 

 here are somewhat peculiar, in exhibiting usually from two to 

 four isolated strands of soft bast. The ducts vary much in 

 size ; but there are usually two of very large calibre (about 

 Y^ of an inch) in each bundle — a very common occurrence 

 in monocotyledons. The ducts are formed of much elongated 

 (;ells — fully half an inch in length — applied to each other 

 by more or less oblique extremities, the obliquity being 

 often so great that the septa become nearly vertical, and, 

 of course, much elongated. In form these septa a,re more 

 or less elongate-oval, with narrowed and almost pointed 

 extremities. They are exquisitely marked, in the middle 

 with transversely elongated pits exhibiting irregularly 

 scalariform arrangement ; this passing rather suddenly 

 towards the extremities into very minute dotting. Like 

 the persistent septa across the ducts in Bovgainvilka those 

 ]h Tcdudinaria are imperforate. 



