DILLENIACEJE. 117 



centric areola due to the presence of the canal which abuts on this 

 perforation. In Candollea and lUbbertia, we find the same general 

 arrangement of the pores, but the areola is more or less distinct 

 according to the species, so that we find every intermediate stage 

 between ordinary non-areolate pores, and pores with large areolae. 

 This also occurs in Curafella, Sc/itimacheria, and as is rather re- 

 markable, in Ad'midia, whose affinities to the Billeniacece are not 

 recognised by all botanists ; in A. callosa especially, the pores are 

 very distinctly areolate. Most usually these pores are arranged in 

 two opposite vertical rows in each fibre. "When the punctations 

 and areola) are quite circular, we can superpose those of one row on 

 those of the other, so exactly that only one set of punctations is 

 seen. But when they are elliptical, as frequently occurs in 

 Dillenia and Candollea cuneiformis, the black elongated spots formed 

 by those of one row may slant in a different direction to those of 

 the other ; so that seen by transmitted light the two spots form a 

 little St. Andrew's cross, with four nearly equal branches very 

 regularly arranged. 



" In the young branches of some of the CandoUeas the liber 

 fibres are relatively very large, separate from one another, and few 

 in number. In several Hibbertias, another element of the bark, 

 the cellular tissue, is greatly developed. But this sort of hyper- 

 trophy only occurs on two sides of the stem, which thus becomes 

 flattened, with two projecting angles ; the wood is not affected by 

 this deformity, which has no relation to that which produces the 

 cladodia described above. 



"The leaves have usually a heteromorphous parenchj^ma; the 

 cells beneath the superior epidermis are rod-shaped, and of nearly 

 equal size ; but they become irregular next the inferior epidermis, 

 which consists of cells of very irregular contour, and bears storaates, 

 which are elliptical in Dillenia^ Candollea, &c. We have said that 

 the parenchyma often contains bundles of raphides; these, projecting 

 from the organs, give the leaves of most Billeniacece the property 

 of becoming rough to the touch when dry. This roughness, not 

 without its practical utility, is due in several species to a somewhat 

 different cause. Some Billeniacece, especially the Ciiratellas, are 

 known to possess leaves so rough and rasping, as to be used in 

 several countries of tropical America for pohshing even metals. 

 This is due to the accumulation in the leaves of a large number of 



