285 



Tests, — 



Three pieces i foot by i inch in a transverse stress gave the following results : — 



1. Broke at 550 lb., deflection -29 inch. 



2. Broke at 530 lb., deflection -36 inch. 



3. Broke at 500 lb., deflection -25 inch. 



(ft) Anatomy. 



Viewed microscopically the various sections of the xylem present differences 

 from some of its congeners. The medullary rays run along the field of view in 

 distinct broad bands with well-defined end and lateral walls, as well as distinct 

 simple pits, which give it the appearance of a number of bolted iron plates (Figure 

 202) ; these parenchymatous cells are narrower than in the other species. There is 

 also a distinguishing scarcity of the brown manganese compound in the cells of 

 the tracheids, those found being distantly scattered throughout the two seasons' 

 growths. 



The bordered pits occur on the radial walls and in a tangential section are 

 less prominent (in section) than in other species. The free edges scarcely protruding 

 into the lumina of the tracheids. In examining these bordered pits under a DD 

 objective (Zeiss), the limiting lamella (torus) is seen to be more enlarged on both 

 sides than in any other species examined, whilst in almost every case there appears 

 to be only one opening into the tracheid instead of two, such as obtains in other 

 species, the opposing wall of the tracheid being quite entire. 



In a transverse section the walls of the autumnal growth are, perhaps, 

 thicker than the others, and the cells are flatter, giving the annual ring a rather 

 pronounced appearance, the transition from the spring growth showing little or 

 no gradation, as shown in Figure ig8, which section depicts a narrow band of 

 autumnal tracheids, such as obtains in this species, across the plate from left to 

 right just above the middle. There are two medullary rays in the left of this 

 figure, the longer and darker is towards the middle. Only a very few tracheids 

 have brown manganese compound contents, and there is none in the rays. 

 Figure igg is a portion of Figure igS more restricted, while Figure 200, a tangential 

 section, shows the prosenchymatous nature of the tracheids along with other 

 characters specified under these plates. Figure 201 is a radial section shov\dng a 

 single row of pitted cells on the walls of the tracheid, and Figure 202 gives a radial 

 section with two rays, and also shows a double row of pitted cells in the tracheids, 

 a rare occurrence in Callitris. Figure 203 is a higher magnification of a portion 

 of Figure 202, and the double rows of pitted cells are more plainly visible, whilst 

 the parenchymatous nature of the whole of the ray cells is well depicted. 



(c) Chemistry. 

 (Vide Chemistry of products of this wood, page 62.) 



