2og 



marked distinction is noticed between the two barks, caused by an irregularity in 

 the disposition and shape of these organs of structure. Thus in this bark the 

 conspicuous feature is the proportionately large area taken up by the parenchy- 

 matous and tannin cells, the former being much flattened radially, and so widel}' 

 separating the bast fibres, which in this case are quite small bodies (hence its less 

 fibrous character comparatively with C. glauca), and occur in broken concentric 

 rings, whilst the companion sieve tubes are also much restricted in size. The 

 oleo-resin cavities, although more abundant than in C. glauca, yet are smaller in 

 size, and the bands of periderm are narrower and very much fewer in number 

 than in C. glauca. 



Figure 140 is a cross section through the junction of the inner and outer 

 bark (one third of the picture from the top) and gives a general idea of the 

 difference between it and C. glaiica. 

 The light irregular bands stretch- 



ing from left 



to 



right are the 

 parenchymatous cells showing 

 their radially flattened cell walls. 

 The bast fibres can be traced by 

 the zig-zag, broken black lines 

 extending from left to right, but 

 being so small their individual 

 outline cannot be well traced. 



The oleo-resin cavities are 

 seen to be smaller than in most 

 species. The black patches in the 

 outer cortex are the manganese 

 compound contents of the paren- 

 chymal ous cells. 



Figure 141 is a cross sec- 

 tion taken near the external edge 

 of the outer cortex, and is given 

 to illustrate a band of periderm, a 

 rather inconspicuous feature in this bark. 



Figure 140. — Transverse section tlirougii inner and outer bark, tlie 

 latter towards the top. Tlie bast cells are not all regularly 

 concentric, as obtains in some other species of CaUitris, 

 and form irregular narrow broken lines from left to right. 

 These are separated by very small sieve tubes and unusually 

 large parenchymatous cells. A few oleo-resin cavities are 

 seen in both barks. C. calcarata, x 70. 



(c) Chemistry. 



The bark of this species appears, chemically, to be distinct in some 

 respects from the other Callitris barks, with the exception, perhaps, of C. arenosa. 

 It is of a darker colour than that of C. glauca, and in the larger trees is more 

 compact and "corky" externally; in section it is a light brown colour in the 



O 



