32 THE TRANSVERSE SECTIONS OF PETIOLES OF EUCALYPTS 



Characteristic features : 

 Section. — Large. 



Hypoderma. — Generally hvo cells thick. 

 Cortical Cavities. — Small and few. 

 Central Canals. — Normally two, but liable to variation ; about same size 



as the largest of the cortical cavities. 

 Hard Bast. — In irregular patches. 

 Wood-curve. — Slender, and horns approaching each other, sometimes very 



closely. 

 Vessels. — Comparatively large, numerous, absent from lower portion of 



wood. 



Kemarks. — Cortical cavities are certainly present in this species, but they are 

 few in number, and many sections of a series show none. They are likewise small, 

 indeed the smallest of any species examined. 



The normal number of central canals is two, but occasionally there may be 

 three or even four, as in one of the sections photographed. The occurrence of four 

 canals is rather interesting in view of the fact that they were found in sections taken 

 near the base of the leaf-blade. It would appear that while the normal number of 

 two usually occurs in the body of the petiole, as the lamina is approached each 

 divides into two before entering the mid-rib. 



II. — Form Confined to Victoria. 



14. E. alpina, Lindley; alpine gum. 



Shrub. 



Leaves. — Very thick, broad, blunt, equally green on both sides. 



Size of Section. — About IJ lines broad and thick, or as broad as thick. 



Outline of Section.— Usually rounded. 



Epidermis.— Thickness, gig in. below, 4 in. above. 



Cortical Cavities.— jIj in. roundish, numbering from 15 to 6. 



Crystals.— Very few. 



Hard Bast.— Well-developed, generally continuous, and several cells thick. 



Wood-curve (see Fig. 24).— With thickened body and gently incurved shorthorns. 



Vessels.— Largest, j^ in. 



Average, ^i, in. 



Medium-sized and moderately numerous, principally occupying middle 



tract of wood. 



