AUSTRALIAN MELALEUCAS AND THEIR ESSENTIAL OILS. 377 



Plate XIX. 

 Fig. 4. This is a higher magnification of the midrib or main 

 bundle in Fig. 3. The dark cells are sclerenchymatous tissue, 

 and this is now seen to much greater advantage here than in 

 that figure. The larger crescent shaped cluster is towards the 

 underside of the leaf, the concave face butting on to the 

 phloem with its cell walls scarcely discernible. The xylem 

 cells succeeding these upwards have thicker cell walls and 

 are quite distinct. The larger cells in the outer field are 

 those of the spongy parenchyma. x 450. 



Plate XX. 

 Fig. 5. This is another section of a leaf cut without bleaching 

 out the cell contents, consequently the presence of manganese 

 compound is marked by the dark substance in the lumen of 

 the spongy parenchyma. Three oil glands are shown. The 

 chloroplastids are distinctly seen in each cell. x 140. 



Melaleuca gibbosa. 

 Fig. 6. A transverse section of just a little more than half a leaf, 

 the midrib or central vascular bundle being on the left of the 

 picture, to the left of which is a large oil gland, x 140. 



Plate XXI. 

 Fig. 7. A slightly larger section of a portion of a leaf between 

 the midrib and edge, and showing chloroplastids in the cells 

 of the palisade parenchyma. The upper surface of the leaf 

 has the papillose projection of the cuticle. x 150. 



Fig. 8. Similar to figure 7, but a large oil gland is to the right ©f 

 the main bundle in this case, thus showing how irregularly 

 the oil glands are distributed throughout the leaf. x 140. 



Plate XXII. 

 Fig. 9. A cross section through more than half a leaf, towards 

 the petiole. x 110. 



Plate XXIII. 

 Fig. 10. A cross section through the centre of a leaf towards the 

 petiole, showing how the palisade parenchyma is displaced by 



