208 M. B. WELCH. 



EUCALYPTUS OIL GLANDS. 

 By M. B. Welch, b.Sc 



With Plates XI -XIV. 



[Bead before the Royal Society of N. S. Wales, December 1, Ll)20.~] 



The literature dealing with the Eucalypts is rather exten- 

 sive, the species of the genus having received, in recent 

 years much attention, particularly at the hands of sys- 

 tematists, technologists and chemists. The anatomy of 

 the various parts has perhaps been least investigated, and 

 so in this paper it is proposed to give the results of some 

 observations of the oil glands, their contents and structure. 



At the present time Eucalyptus oils are receiving much 

 attention in the pharmaceutical, perfumery and general 

 industries and the production of this commodity has 

 attained very large proportions. The prominence which 

 this industry has now reached lias led me to investigate 

 the oil in situ in the gland itself. 



The oil glands, as they are usually termed, occur in the 

 leaves of almost every species but in varying number, 

 reaching perhaps a minimum in the Blood woods; e.g., E. 

 termlnalls, where they are practically non-existent, and a 

 maximum in the leaves of some of our Mallees, e.g., E. 

 polybractea, E. costata and others. They reach a com- 

 paratively large size in leaves with a width of less than 

 0*5 mm. while yet in bud. These glands also occur in the 

 petioles, young stems, calyx, operculum and even in the 

 fruits. In the case of barks, oil is rarely found, but never- 

 theless exceptions occur in that of E. Bridgesiana and E. 

 Macarthuri. An examination of the bark of E, Macarthurl 



