144 



as so manv concentric white rings, being more pronounced in the darker outer 

 bark or cortex, and where, after the oil of the cell has been volatilised or removed, 

 resin or sandarac, as it is called, remains as a white solid, filling the cells and 

 giving the appearance of tangential parallel bands or rather rows. In the living 

 bast or inner bark the cell content is in a liquid condition, and on a cut being 

 made into fresh specimens there flows at once a liquid, which, however, indurates 

 into beads or tears as soon as the ^'olatile jiortion has evaporated or altered. 



Figures 90 and 91 longitudinal sections) show these bodies to be cavities 

 rather than resin ducts or canals, and this is further proved by the small flow of 

 liquid from a cut in the bark, which is quite a reverse order of things to that found 

 occurring in the American Conifer bark and wood which yield the " naval stores " 

 of that country, and give a continuous flow for a whole season when cut, thus 

 proving that they are in that case canals that have been tapped. Microscopically 

 these cells are found to be not quite so regularly arranged as appears macroscopi- 

 cally, but, nevertheless, their numerical strength is even then well emphasised, 

 as shown in the transverse sections in Figures 92 and 93. The anatomical structure 

 is interesting in that the variety of vessels is limited. The cambium is succeeded 

 by concentric rings of cells of three distinct characters. 



The most noticeable concentric row is that composed of cells of sclerenchy- 

 matous bast fibres with their much-thickened walls. These uniseriate concentric 

 rings of bast cells are generally separated from each other by three rows of cellsj 

 a regularity that is rather unusual, as it does not appear to have been observed 

 before in other Conifers, the general rule being consistently three or four inter- 

 vening rows. The middle row of these cells, is of a parenchymatous nature, and 

 these are often filled with manganese compound, especially in the outer cortex, 

 and sometimes found longitudinally flattened, whilst at other times they are of a 

 lysigenous character, for, becoming extended, they push out, or flatten as it were, 

 the contiguous cells on each side of it and the sclerenchymatous bast cells. 

 The intervening cells between these parenchymatous and bast ones are sieve tubes. 



At irregular intervals are concentric bands of periderm or cork cells, more 

 especially in the outer cortex. 



Irregularly scattered throughout the mass, it is found some of the cells of 

 ' the parenchymatous bands have tannin content determined by the usual tests. Al- 

 together there is a regularity of successive layers of the different cells similar to 

 that which appears to characterise some of the Conifers of the northern hemisphere 

 (vide de Bary, p. 494; also " Some North American Coniferfe," E. S. Rastin and 

 H. Trimble^, but differing from some of the American Conifcra; barks figured by 

 Bastin and Trimble. The medullary rays are not so pronounced as in the xylem, 

 the particular feature being the numerous perforations of the conmumicating 

 aperture with the lumen of the contiguous tracheids. 



