36i 



the base, midrib not more developed than the numerous lateral veins, very 

 sharply pointed. ]\Iale amentum is sessile, arranged in closely and spirally packed 

 catkins* towards the end of the branches, sometimes over 6 inches long, and ^ inch 

 in diameter, the imbricate scale-like apices of the stamens four-sided. 



Fruit cones on the higher branches, ovoid, globose up to 12 inches 

 high, and g inches in diameter ; the scales imbricate, 4 inches long and 3 inches 

 broad, tapering towards their winged base, the point of the sporophyll recurved and 

 spinescent. A cone 10 lb weight was obtained from a tree, having also male 

 catkins. 



III. LEAVES. 



(«) Economic (none known to us). 



(b) Anatomy. 



A cross-section of the outer portion of a leaf is given in Figure 251, which 

 gives a fair idea of the position of the various cells in that portion of the leaf, 

 and similar to the other structure, 

 which goes to make up the whole 

 leaf substance. 



The assimilatory surface is 

 the outer one, and the cuticle of 

 this is backed by a single row of 

 ver\' numerous, small, epidermal 

 cells, followed by one of thick- 

 walled hj^podermal cells, and these 

 in turn are succeeded by a row 

 of palisade parenchymatous cells, 

 having their long axes at right 

 angles to the cuticle, and forming 

 about a third of the whole leaf 

 tissue, although absent from the 

 transpiratory surface. 



The epidermal and hypo- ^ ' 



dermal cells extend right round 



the leaf but the latter are packed at the edges of the leaves, and more pronounced 



on the outer surface. 



Figure 251. — Transverse sectiori through one edge of a leaf, sho^-ing 

 how the h3rpodermal cells are packed below the single 

 row of epidermial cells at the extreme edge. One oil gland 

 surrounded by secretory cells is seen to the left, and to 

 the right is a bundle surrounded by endodermal cells. The 

 two rectangular black patches on the palisade parenchyma 

 are manganese compound from their original cells. .4. 

 Bidwilti, X 260. 



*To determine the amount of pollen, two of the green but mature catkins were taken. They each measured 

 13 centimetres long, b^- a mean diameter of 16 millimetres. They were placed in glass dishes on 22I9/09, and bj" the 

 14th of the following month the whole of the pollen had been shed, the catkins then being quite dry. The pollen 

 was sulphur yellow. The amount shed by one catkin weighed i -2946 grams, and that from the other i '626 grams, 

 or together 2-9206 grams. 



