i85 



conical projections, at the base of which are found the stomata, as well as on the 

 inner surface of the free portion of the leaf, and on the opposite dorsal surface 

 of the decurrent leaf, but only on that portion of it immediately covered by the 

 free end. On the dorsal side, the epidermal cells are backed by a single row of 

 hypodermal cells and again by palisade parenchyma; the spongy mesophyll 

 occupying the bulk of the leaf substance. 



The endodermal parenchymatous cells are not much in evidence, there 

 being an unusual number of transfusion tracheids around and between the leaf 

 bundle and the central bundles of the branchlet ; one or two sclerenchymatous 

 cells were detected just on the outside of the phloem of the leaf bundle. 



The oil cavities are fairly numerous and large, and are surrounded by 

 strengthening and secretory cells. 



A cross section through the decurrent leaves shows distinctive characters 

 that aid in establishing the specific rank of this Callitris, vide Figures 121, 122. 



The central cylinder of the branchlet is composed of bundles (generally 

 three) having very thick-walled cells in the xylem and a phloem also unusually 

 thick, these being separated medullary by the usual pith tissue of the central 

 column, which latter is not surrounded by the usual parenchymatous cells, 

 whilst the transfusion tissue is well developed, vide Figure 123. 



A small bundle occurs as usual along the inner side of each leaf (and 

 between the base and the oil cavity, if the latter be present) in the section, and 

 surrounded by the fundamental tissue. 



The oil cavities have exceptionally large diameters, and have strengthening 

 cells, as well as secretory ones, as shown in Figures 121 and 122. 



The assimilatory surface is on the superior side, and the transpiratory on 

 the inferior. 



The epidermal cells are in a single row below the former, and this is subtended 

 by a single row of hypodermal cells which, if anything, are larger individually 

 than epidermal cells. 



The two Figures 123 and 124 illustrate the features above recorded. 



(c) Chemistry of the Leaf Oil. 



Material of this species was collected at Tal Tal Mountain, near Bylong, 

 New South Wales, 240 miles from Sydney, on the 22nd March, 1905. The terminal 

 branchlets with fruit were distilled for six hours, and the yield was somewhat 

 large; 480 lb. of material gave 55^ oz. of oil, equal to 0-723 per cent., which is 

 the greatest yield obtained with the leaf oil of any species of Callitris. The 

 crude oil was but slightly lemon-coloured, and had the usual odour, although 



