AS AIDS IN THE DETERMINATION OF SPECIES. 31 



Eemabks. — While two is the normal number of central canals, there may be 

 only one, or as many as four. 



The sections from one petiole showed only a single canal near the base, but the 

 normal number (2) near the leaf-blade. The two main canals were also foimd in 

 several instances to divide into four on passing into the midrib. Probably this is a 

 normal occurrence in this species. 



The contents of the canals were tested with various reagents. When treated 

 perfectly fresh they readily dissolved, but after long steeping in water, they became 

 hardened and insoluble in the ordinary reagents. Under these circumstances they 

 would not dissolve either when warmed in nitric acid or in potash and glycerine. 

 Nitric acid gave a red tint, and potash a brown, but that was all the change observed. 



In the section of the young stem it is interesting to observe that central canals 

 are absent, while the cortical cavities are present. The latter are very numerous, just 

 as in some sections of the leaf stalk. Tlie hard bast is not of equal thiclmess 

 throughout, nor is it always continuous, although it is shown thus in the drawing for 

 simplicity. Only the larger vessels of the wood are figured. 



13. E.ficifolia, F. v. M.; scarlet-flowered Eucalypt. 

 Tree. — Seldom exceeding height of 60ft. 

 Leaves. — Generally resembling preceding, but not so broad in proportion to 



length. 

 Size of Section.— 1 J lines broad by 1 line thick, or 1 J times broader than thick. 

 Outline of Section. Varying from round to oval to a much depressed semi-circle. 

 Epidermis. — Thickness, ^ — i in. 



Breadth, ,55 in. 

 Hypoderma. — Equal to epidermis in thickness, and usually a two-celled layer. 

 Cortical Cavities. — About ^ in., few in number, or absent. 

 Central Canals. — Normally 2, but occasionally 3 or 4; roundish. 



Largest, about i in. 

 Crystals. — Numerous. 



Hard Bast. — In irregular patches, a few cells thick. 

 Wood-curve (see Figs. 23 and 23fl). — Generally slender, and with horns curving 



gently, and sometimes almost meeting. 

 Vessels. — Largest, ^ in. 



Average, about ^ in. 



Comparatively large and numerous, and distributed towards upper 

 and middle portions of wood. 



