316 APPENDIX IV 



In the autumn-wood there are a few, widely scattered, much smaller pores, 

 with sma^l areolae of soft tissue. The fine, uniform pith-rays are of a brick- 

 red against the cinnamon-brown wood, and are distinctly seen as they bend 

 round the large pores in the spring-wood. The East Indian Cedrela Toona 

 is a very similar wood. 



Passing on to woods in which the vessels or pores, though not equally dis- 

 tributed throughout the rings, are not larger in the spring-wood than in the 

 autumn-wood, we come to those of the genus Prunus (the Plums and Cherries), 

 in which the pith -rays are distinctly visible, and the Buckthorns and Sumachs 

 {Bhdmnus and lihus)^ in which they are not so. The wood of Rhdmnus 

 catMrticus, the Buckthorn (Plate XXV.), presents a striking object under the 

 microscope, on account of the flame-Hke branching groups of pores, often 

 fifty together, which extend from broad bases on the inner margin of each 

 ring to its outer limit. This structure does not occur in other species of the 

 genus, such as the British B. Frdngula, the so-called "Berry-bearing Alder," 

 or the Canadian R. Purshidna, which is figured by Mr. Stone. The heart- 

 wood is orange and the sapwood yellow. 



The Venetian Sumach, or Wig-tree of our gardens [Rhus Cotinus), figured 

 on p. 50 (Fig. 35), has a hard, greenish or golden heart- wood, which is used as 

 a yellow dye. The rings are well marked under a lens, the large pores of the 

 spring-wood gradually diminishing in number and size outward, and being 

 grouped two to seven together. 



The " diffuse - porous " woods comprise most of our European broad- 

 leaved trees. Their annual rings are very generally distinct ; but they owe 

 this distinctness, not to any predominance in number of size or the pores in 

 the spring-wood, but to the closer texture of the elements of the autumn- 

 wood (Plates XXVI. to XL.). 



If we divide this large group into those with large and those with minute 

 vessels, the Wakuts, Sal, and, perhaps, most of the Eucalypti, constitute the 

 former division, though possibly these last may be better placed with tho 

 " false-ring " types. 



Mglans nigra, the American Walnut (Plate XXVI.), the species now most 

 in use, has its rings bounded by a fine line just traceable with a lens, but not 

 noticeable in solid specimens of the dark wood. There is an ill-defined pore- 

 ring of an interrupted row of moderately large, open, oval pores ; and those 

 scattered, fairly evenly, through the later-formed wood, somewhat in echelon, 

 are smaller. They are often subdivided radially into two to five. The 

 numerous pith-rays are not visible to the naked eye, are slightly undulating, 

 and bent round the larger pores. Pine, short, transverse lines of soft tissue 

 occur, but are very inconspicuous. Mglans cinerea, the Butternut or White 

 Walnut of the United States (Fig. 36, p. 351), is a softer, lighter wood, with 

 practically identical structure. 



Karri, Eucalyptus versicolor (Plate XXVII.), is a dark-red, hard, and 

 heavy wood. Its rings are sometimes marked by a dense zone in contact 

 with one having crowded pores. The pith-rays are very numerous, uniform in 

 width, equidista,nt, waved, and avoiding the pores ; but not recognizable by 



