INTRODUCTION 



as the oblique section of any figure exhibits greater breadth 

 than a transverse section, it is a wise plan to use the knife freely 

 in all directions to show up obscure details. This coat of 

 soft-tissue may be traced in transverse section (across-grain) 

 in all grades of complexity. The simple uniform sheath is some- 

 times laterally extended into wings or diamond-shaped patches 

 having a large pore or pore-group as centre (Fig. 47), or into 

 concentric rings, or oblique, cross-shaped or undulating lines or 

 bands (Fig. 53), which look like designs in lace when viewed 

 as transparent objects. Some are of great beauty and many 

 are so characteristic that they at once declare that such a 

 timber belongs to such and such a genus. For the most part 

 the pores and soft-tissue together produce this tracery, but 

 occasionally the soft-tissue is quite independent of the pores 

 (Fig. 55), and nearly always is of a lighter colour than the 

 ground tissue. 



The term " soft-tissue," adopted from Gamble, is rather a de- 

 fective expression, and I should not use it did I think that 

 the word " parenchyma " served the purpose better. Nord- 

 linger uses the word " weitlumige," which is difficult to express 

 in English in a single word. Soft-tissue may be very hard tissue 

 at times, but it is always softer than the wood fibres of the same 

 timber, and to the lay mind the term has the advantage of con- 

 veying the meaning intended, for in looking at a section of wood 

 no one would misapply it. 



In its simplest form the soft-tissue occurs as odd cells scattered 

 here and there, or as strings of single cells. If these strings be 

 sufficiently numerous and confined to certain spots, they may 

 form patches or bands. It is only when they constitute defined 

 areas that they can be described by definite names, so mere 

 sporadic cells, strings or shapeless indefinite patches will be 

 referred to as such. 



Gamble makes a provisional classification of the Leguminoseae 

 (Bean and Mimosa family), by means of their soft-tissue, and 

 relies to some extent upon the breadth of the bands. This may 

 suffice within the limits of the species found in India, but as soon 

 as a larger field is entered upon it becomes inadequate. In 

 many other species the breadth of the zone is extremely variable, 

 and again some soft-tissue may be present in well developed 

 rings, and yet be quite absent from the slowly grown wood 

 (Fig. 145). Soft-tissue is usually present among the dense 

 mass of pores in the pore-rings of woods that possess them, 

 but it should not be considered in the same light as a zone 

 enclosing the pores, but as the result of crowding, and may be 

 ignored as of little significance. As the pores diminish towards 

 the Autumn zone, and the intervals increase, the soft-tisMir 



XXV 



