THE OCCURRENCE OF OIL-GLANDS IN THE BARKS OF CERTAIN 

 EUCALYPTS. 



By M. B. Welch^ B.Sc, A.I.C, Economic Botanist, Technological Museum. 



(Plates xlviii.-xlix. ) 



[Read 27th September, 1922.] 



The occurrence of secretory glands containing an essential oil in the leaves 

 of plants is typical of a number of Natural Orders, particularly in the Myrtaceae 

 and Rutaceae. In the ease of the barks, however, oil glands are comparatively 

 rare and Solereder (1908) records them in his generalisation only in the Samy- 

 daeeae and Myrtaceae. Under the Myrtaceae, however, Solereder states, "The 

 improbable statement of MoUer's (Rindenanatomie, pp. 344-347) as to the oc- 

 currence of resin spaces in the secondary bast in Eucalyptus viminalis and E. 

 Stuartiana, F.v.M. requires re-examination. According' to Moller spherical (0.12 

 mm. diameter) apparently lysigenous resin spaces occur in the first named 

 species." Unfortunately a copy of MoUer's work is not available for reference, 

 but under E. viminalis, Mueller (1879-84) gives "an abridged translation" from 

 it, which reads as follows: — "The periderm contains rows of almost cubic partially 

 unilateral-sclerotic cork-cellules, and reaches quite to the bast; the latter is 

 scalarif orm-laminated through isolated or not far extending plates of fibre-bundles ; 

 the fibres of the bast are about 0.03 mm. broad, and accompanied by chambered 

 fibres (Kammer-Fasern), which contain prismatic ci-ystals, similar to those oc- 

 curring in the bast of elms, and such crystals are scattered also through the soft 

 bast; the latter consists of small cellules, is thin-walled and beset with roundish 

 Kino-spots; the sieve-tubules (Sieb-Rohren) have the narrow perforated plates 

 numerously ladder-lUie arranged (Stein-Zellen) ; the medullary rays are one- or 

 two-rowed, are never sclerotic and contain, no crystals." 



It will be noticed that in this translation no mention is made of "resin- 

 spaces" and the neai'est approach to them is found in the words "roundish Kino- 

 spots." Mueller makes no mention of the bark anatomy under E. Stuartiana, as 

 apparently that portion of the Eucalyptographia was completed before 1882, the 

 date when MoUer's Rindenanatomie was published. In spite of Solereder's 

 doubts as to the correctness of MoUer's work, the presence of an essential oil 

 in the barks of certain Eucaly^Dts can no longer be disputed. 



In 1898 Baker (18P8, p. 166) obtained an essential oil from a steam dis- 

 tillation of the bark of E. Bridgesiana and later H. G. Smith (1916, p. 177) 

 gave au analysis of the oi? obtained in a similar manner from the bark of E. 

 Macarthuri. In Eucalyptographia, under E. pulverulenta, Mueller mentions that 

 this tree is sometimes known as "Turpentine" on account of the "peculiar some- 

 what terebinthine odour" in tlie bark. This reference is evidently in connection 



