140 Mr Nicol o7i the Structure of 



leaved pine called Cheir, from Fora, opposite Gospoor, — the fir 

 from Nepaul, and in the Bailee fir. 



When a transverse section of any of the Coniferce of the re- 

 quisite thinness is viewed with a lens of the requisite magnifying 

 power, a reticulated texture is seen, which bears a considerable 

 similitude throughout the whole species. Rays or lines of dif- 

 ferent degrees of thickness appear extending from the pith to 

 the surface. The boldest of these often preserve a rectilineal 

 course, but some of the more slender kind have, in some places, 

 a kind of zig-zag form. The whole are connected by concentric 

 lines or partitions, occasionally also varying a little in thickness. 

 The meshes or network resulting, must consequently sometimes 

 varv a little in form. When two or more radial lines are equi- 

 distant and nearly of equal degrees of thickness, the concentric 

 lines cross them at nearly right angles ; but, as the distance be- 

 tween the concentric lines is generally greater than the distance 

 between the radial lines, at least near the inner side of each 

 layer, the meshes or openings are a little elongated in the direc- 

 tion of the radii. Towards the middle of the layers the meshes 

 become nearly equilateral, and towards the outer edge of the 

 layers the concentric partitions approximate each other, when the 

 meshes become elongated in a direction perpendicular to the radii. 

 This description will, in general, be found to apply to many 

 pines, at least when they have attained a slow and consequent 

 uniformity of growth. Near the pith where the annual layers 

 are generally broad, and, of course, the process of vegetation had 

 been rapid, the meshes often assume a considerable diversity of 

 form. They are sometimes pentagonal, sometimes hexagonal, 

 and sometimes of no very definite form. In some pines, the 

 partitions at their points of intersection increase a little in 

 breadth, especially when the slice is of a certain thickness, which 

 gives rise to a subhexagonal form, and which is sometimes more 

 frequent in one tree than in another, even of the same species. 

 The quadrangular form of the meshes, I have frequently ob- 

 served to be much more conspicuous in some of the large 

 American than in several of the European pines of the same 

 species. In a Pinus Abies, for example, of large dimensions, from 

 the forest of Braemar, in Aberdeenshire, the irregular was much 



