97 



Bordered pits are very numerous on the radial walls, equalling in diameter 

 that of the lumen. They also form a conspicuous object on these walls in a 

 tangential section, being cut diametrically, the lumella being clearly defined in 

 Figures 47 and 48. These sections also show the cells of the medullary rays to 

 be empty of manganese compound, an exception to the rule. 



Figures 45 and 46 are gi\'en to illustrate the distribution of tracheids con- 

 taining the so-called " resin " (indicated by the black spots), in the autumnal 

 and spring growths of the timber. Figure 47 is a tangential section through 

 spring growth ; the lumina in this case being free of manganese compound 

 as also are the cells of the rays which are seen to vary in height according to the 

 number of rows of horizontal cells. Several of the radial walls are strongly marked 

 with bordered pits sectioned, and show in this species their disposition in the walls 

 of the tracheidal cells, the prosenchymatous nature of which is shown in 

 several instances. Figure 48 is a 210-magnification of the central portion of 

 Figure 47^ and brings out more clearly the structure detailed above. Figure 49 

 illustrates a radial section of the timber of this species. The dark vertical lines 

 are the manganese compound content of the tracheidal cells. The lighter portion 

 to the right is the spring growth, the central ray extending partly through it and 

 the autumnal growth. The bordered pits in the radial walls are faintly seen. 

 Dr. H. Tassi has microscopically examined the timber of C. robusta (" Bull. Lab. 

 Orto Botanico di Siena," Vol. Ill, Fasc, 1-4, p. 12), but to which species in this 

 work it refers we were unable to ascertain, not having seen the publication. 



(c) Chemistry. 

 (See articles on the Phenol and the occurrence of Guaiol, &c.) 



• V. BARK. 



(a) Economic (vide Chemistry). 

 (&) Anatomy. 



The inner cortex appears to be free from periderm or cork layers, these 

 occurring only in the outer bark and then in numerous concentric bands. 



The cambium is succeeded by regular uniseriate rings of sieve-tubes, paren- 

 chymatous cells and bast fibres, and this order of structure is followed in the 

 outer bast, except that at almost regular intervals periderm layers occur. 



Oleo-resin cavities are perhaps smaller than those of most species. 



Figure 50 is a section taken from the junction of the inner and outer 



cortex. The former has a regularity of cell arrangement not so well defined as 



in the latter, where in this instance the resin cells are more numerous. The three 



hght bands running from left to right in the upper half of the picture are the 



G 



