jj-' 



radial walls show series of pitted cells in section. A radial section is given in 

 Figure 241 with two medullary rays on the left of the plate, and their short 

 axes walls show them to be parenchymatous in character, and further they are 

 all empty, or at least have no dark substance in their cells in this instance, and 

 what is of further phylogenetic importance the outer cells are identical in character 

 with the inner ones — features that seem to point to a recent (geological) evolution 

 of the genus. 



In these plates (Figures 242-5) will be seen on almost every tracheid wall, 

 double or triple contiguous rows of pitted cells, exactly as obtains in Agathis {Dam- 

 mara), a fact that establishes a connection with these congeners of the forest of 

 past geological times, and is in contradistinction to the uniform single row of 

 Callitris. These pitted cells are shown under a 210-magnification (Figure 245); 

 only rarely are pitted cells found on the tangential walls, — a generic difference 

 from Agathis robusta. 



The simple pits, which commtmicate with the lumina of the tracheids by 

 circular perforations are comparatively numerous, ranging in number from six to 

 ten, as against two to four in Callitris (Figure 246). 



V. BARK. 



(a) Economic (vide Chemistry, infra — Chemistry of the Latex). 



(6) Anatomy. 



One reason for working upon the mature bark of this and the cognate 

 species, A. Bidwilli, was to try and trace the origin of the respective exudations, 

 at this stage of the tree's age, which are fully dealt with under their chemistry. 



The barks resemble each other in some characters, although their exudations 

 differ in their several constituents, that of A. Cunninghamii containing most 

 oleo-resin, whilst A. Bidwilli yields gum principally. 



This latter substance also occurs in this species, for what is probably 

 one of its conveyors (bast fibre) is distinctl)/ seen in Figure 247, on the right- 

 hand side of the picture, just below the periderm — the white band in the middle 

 of the picture ; and just below this can be seen a stone cell, showing that these are 

 apparently two distinct substances or structures. 



The composition of the bark is even less regular than in A. Bidwilli, for 

 with the exception of the concentric periderm layers nothing else is regularly 

 arranged, and these occur in parallel bands on the outside of the cortex. Stone 

 cells are found scattered throughout both inner and outer cortex, as also are the 

 oleo-resin cells. Figure 248, in fact, the above together with parenchymatous cells, 

 and sieve tubes, compose the whole bark substance. 



