AUSTRALIAN MELALEUCAS AND THEIR ESSENTIAL OILS. 207 



stituents, similar to that existing between the venation of 

 the leaf and the oil constituents of the Eucalypts. 



(1). Melaleuca nodosa, Sm., in Trans. Linn. Soe. Ill, 276, 

 and Exot. Bot. t. 35: 

 Botany.— (a) Systematic. — A fairly tall shrub, mostly 

 found growing in dense masses rather than in individual 

 trees, and generally known as "Tea Tree Scrub." The 

 leaves vary in shape and length ranging in the former case 

 from flat to almost terete, and measuring from half to 

 nearly two inches in length; are rigid and pungent pointed. 

 The flowers and fruits are well described in Bentham's 

 Flora Australiensis, Vol. ill., p. 158, where also will be 

 found a list of the species synonymy. Its geographical 

 range extends from the Blue Mountains to the Queensland 

 border, and it may therefore be regarded as a coastal species. 



(b) Histological. — A transverse section of the leaves 

 gives quite an oval figure as shown in the illustrations, and 

 there appears little to indicate either the upper or lower 

 surface of the leaf except the orientation of the phloem 

 and xylem of the central vascular bundle (midrib), or the 

 shorter longitudinal axis of the parenchyma cells. The 

 convex side of the phloem faces the lower surface of the 

 leaves. Stomata are not shown in any of the sections cut; 

 the epidermic cells form quite a narrow uniform band 

 around the parenchymatous cells of palisade layers. These 

 latter consist of two well marked contiguous rows running 

 uniformly round both surfaces, but slightly shorter in length 

 on the lower one. This uniformity is, as far as our researches 

 go in this direction of the Myrtaceous plants unusual, more 

 numerous layers generally obtaining in the upper surface, 

 although perhaps in this case a set off occurs in the longer 

 parenchyma cells of the upper portion of the leaf. This 

 comparative regularity of disposition of cells we would 

 suggest, indicates an immunity or at least a common surface 



