4d4 OIL-GLANDS IX THE BARKS OP CERTAIN EUCALYPTS, 



development of the regular fibre zones, these being replaced by more or less 

 isolated pitted stone-eells. 



E. cinerea F.v.M. "Argyle Apple." 



Possesses a thick fibrous stringybark, reddish-brown on trunk and longer limbs 

 almost to the branchlets. This tree was, by later botanists, confused with E. 

 pulverulenta Sims. The inner portion of the bark contains numerous oil-glands, * 

 the contents being yellow in colour and almost soluble in 100% alcohol. Average 

 size 0.12 mm. x 0.075 mm. In some cases the glands were not circular or 

 elliptical in section but rather triangular, rhomboidal or pentagonal, up to 0.20 

 mm. in diameter. In smalltwig-s oil-glands were also prominent in the secondary 

 bast. 



E. elaeophora F.v.M. "Bundy or Half Box." 



Has a fibrous bark similar to that of the "Boxes," more furrowed in old 

 trees. Oil-glands numerous, small, up to 0.18 mm., averaging about 0.12 mm. 

 Contents bright yellow, soluble slowly in 100% alcohol. The fibre zones are 

 arranged irregiilarly and are somewhat elliptical in cross-section, thus giving rise ' 

 to the fibrous eharaeter towards the outside. 



E. Gullicki Baker & Smith. '-Blue Mountain Gum." 



Bark usually smooth, mottled grey, resembling E. haemastoma var. micrantha, 

 but sometimes rough on the lower portion of the trunk. On cutting the bark 

 the odour of the essential oil is very noticeable, and provides an easy method in 

 the field of distinguishing this species from the "Scribbly Gum" {E. haemastoma 

 var. micrantha), the two species often growing together. In section, oil-glands 

 are very numerous, the contents being light yellow in colour, usually darker to- 

 wards the outside; and are soluble in 90 to 95% alcohol, leaving a small residue. 

 The fibre groups are not regularly arranged but, nevertheless, are more con- 

 centrated into concentric bands (visible maeroscopieally) from 2 — 3 mm. apart. 

 The glands, though numerous, are rather small^ measuring up to 0.12 mm. in 

 diameter. 



E. maculosa Baker. "Spotted Gum" or "Brittle Gum." 



A tree with a smooth bark, sometimes rough at the base. Oil-glands dis- 

 tributed in outer portion of the bark, fibre zones in distinct concentric rings 

 which are separated by broad zones of thin-walled tissue in which irregular 

 stone-cells occur. The glands are not particularly numerous, and are small, 

 averaging about 0.10 mm. in diameter. Contents soluble in 100% alcohol, except 

 those darker in colour towards the outside. 



E. Smithii Baker. "White Top" or "Gully Ash." 



Bark on young trees smooth, but later becoming deeply furrowed as in E. 

 Sieberiana, and resembling in appearance that of an Ironbark. Oil-glands are 

 particularly numerous and large in this species and are as a rule grouped in 

 large areas of thin-walled parenchymatous tissue, more or less spindle-shaped in 

 radial section and each area separated from the others by large groups of bast- 

 fibres. The glands are quite visible with the naked eye and measure up to 0.3 

 mm. in diameter. The distribution in this species is rather exceptional as the 

 outer bark is divided into two distinct interlacing tissue zones, with and without 

 glands. In a portion of the bark of E. Smithii 3 inches (75 mm.) in thickness. 



