BY M. B. WELCH. 433 



insoluble, becoming less so towards the cambium, with a gradual lightening in 

 colour. From 20 mm. to 30 mm. there are comparatively few glands and the 

 contents are readily soluble, whilst in the inner portion (30 — 40 mm.) glands are 

 practically non-existent. The odour of geranyl acetate, though pronounced in the 

 outer portion, cannot be detected in the inner section. The outer yellow con- 

 tents are insoluble in glacial acetic acid, ether, chloroform, etc. On leaving 

 . sections in glacial acetic acid for 48 hours there was a lightening in colour, but 

 ihe contents were otherwise aisparently quite unaffected. It is apparent, there- 

 fore, that there is a decided alteration in the contents of the oil-glands in the 

 outer portion of the bark, even in those of comparatively small branches. This is 

 evidently due to alteration of the oil to bodies of a resinous nature. Alkannin in 

 50% alcohol gave a definite colouration for oil in the interior glands. There 

 was no indication of tannin in the glands, though ferric chloride gave a definite 

 reaction in the neighbouring cells. An examination of the leaf oil-glands showed 

 the contents to be somewhat sparse, often only a fringe bordering the edge of 

 the cavity, granular, almost colourless and soluble in 80 — 90% alcohol, though 

 leaving a film-like insoluble residue. 



The following descriptions deal briefly with the individual species in which 

 bark oil-glands have been found. 



E. aeaciaeformis Deane & Maiden. "Black Peppermint." 



A tree with a fibrous bark, sometimes rough and furrowed. Oil-glands are 

 not numerous, large, measuring up 0.23 mm. in diameter, contents yellow in 

 colour, less soluble and darker towards the outside. Fibre zones numerous thus 

 forming the rough persistent .outer bark. 



E. aggregata Deane & Maiden. "Black Gum," "Peppermint." 



Bark "Box-like or rather more flaky; between that of a Box and a Stringy- 

 bark or Woollybutt In old trees verj' thick and containing essential oil" 



(original description). Oil-glands fairly numerous, distributed evenly through 

 the outer portion of secondarj' phloem, contents almost soluble in 95% alcohol, 

 darker yellow in colour towards the outside — measuring up to 0.18 mm. in dia- 

 meter. Fibre zones arranged in concentric rings. 



E. angophoroides Baker. "Apple Tree Box." 



A "tree with a white Box-bark, persistent to the ultimate branches" (orig, 

 description). Oil-glands large, up to 0.23 mm. in diameter in the materia] 

 examined. Contents dark, granular, partially filling cavity, soluble slowly in 100% 

 alcohol. They are arranged between the groups of fibres, often 3 — 4 glands oc- 

 curring in a row. Alkannin gave a very definite reaction. In twigs a few mil- 

 limetres in diameter the development of secondary glands was evident. 



E. Bridgesiana Baker. "'Woollyljutt" or "Butt Butt." 



"Bark whitish-grey, wrinkled or tessellated, short and brittle in the grain, 

 not fibrous, almost exactly identical with the Box, E. hemiphloia, when freshly 

 cut giving out an aroma similar to the ordinary oil obtained from Eucalyptus 

 leaves" (original description). An examination of the mature bark sections 

 shows glands measuring up to 0.18 mm., elliptical in cross-section, with the 

 longer axis directed tangentially. Section near the cambium showed no trace of 

 glands. Small twigs also showed marked development near the outer portion. 

 The glands were large, measuring up to .23 mm. in diameter. There is less 



