476 



OCtX'RRKNX'E OF OIL DU(JTS IN' CKRTAIX EUCALYPTS AND ANUOl'UOKAS. 



E. maculata Hook. (PL xliii.. fig. 1), E. peltala Bentli. (PI. xliv., fig. 3), E. 

 pjirophora Bentli. (PI. xlv., fig. 4), E. terminmlis F. v. M. (PI. xliii., tig. 5), 

 E. trachijphluia ¥■ v. M. (PI. xlvi., fig. 3), E. Watt:oniana V. v. M. (PI. xliv., 

 fig. 2), Angophora lanceolata Cav. (PI. xliii., fig. 2; PI. xliv., tig. (j). 



E. corymhdxa, tlie common Bloodwood near Sydney, has been selected as 

 being typical of the above species. 



In the stems these canals or ducts are usually orientated towards the four 

 corners of the pith, which is more or less rectangular in section, and occur just 

 within the intraxylary phloem, the vascular bundles of the Eucalypts being 

 bicollateral. They are typically four in number, though it is quite common to 

 find fewer, and this number is often exceeded. An example of this is seen in 

 E. haemato.Tijlon (PI. xlv., fig. 3) where nine canals occur. In Aiujophora 

 lanceolata the young stems are usually somewhat triangular (PI. xliv., fig. G). 

 This is reflected in the pith and in this species the number of ducts in the 

 stem is commonly three, directed, as in E. corymhosa, to the cornei-s. In a large 

 number of Eucalypts now examined (over eighty species) I have found no 

 indication of ducts occurring — when they do occur — in any [lart of the stem, 

 other than the pith. 



In the leaves, the canals are found only in the mid-rib and never in con- 

 junction with any of the lateral or intramarginal veins. In every species of 



^J 



it) 



Text-fi". 2, 



Te.\t-fig. 1. — Tran^-erse sections of a leaf nine inches in length, showing the 

 diagrammatic arrangement of the ducts and xylem. 



(a) T.S. petiole near stem; (b) T.S, petiole near lamina; (c) 1 inch from base 

 of lamina; (d) 2 inches from base of lamina; (ei 3 inches from base of lamina; 

 (f) 4 inches from base of lamina; (g) 5 inches from base of lamina; (h) 6 inches 

 from base of lamina; (i) 7 inches from base of lamina; (j) 8 inches from base 

 of lamina. 



Text-fig. 2. — Tw-o adjacent ducts in a young leaf of /;. corymbosa which, 

 however, do not show branching. The smaller duct only extends for a very 

 short distance and is independent of the larger one. The shaded cells possess 

 denser contents and are apparently, at this stage, epithelial in character. 



Eiicahiptu.'y in which these ducts occur, the xylem of the principal leaf-vein 

 forms two di.stinct, almost parallel, bands along the greater part of its length. 

 This is shown somcwiiat diagramniatically in Text-fig. 1 (c.f.). 



