I.] GENERAL CHARACTERS AND STRUCTURE. 3 



generative tissue which remains after giving rise to 

 practically the whole of the wood (a very little in the 

 centre excepted) and cortex visible in the woodcut. 

 Since we are not concerned with the cortex and bark 

 at present, it will be convenient to regard the log as 

 '* barked," and only deal with the wood or timber 



Fig. I.— a log of timber, showing radial cracks after lying exposed for some time, a, 

 a large crack extending from pith to circumference ; b, the cortex : Cy medullary 

 ray ; d^ cambium ; e^ annual ring ; y, outer bark, proper. Reduced. . 



itself, in the condition to which the woodman reduces 

 it after removing the cortex with certain implements. 

 If now we split such a log as Fig. i along the line 

 of the big crack, neatly and smoothly, the well-known 

 ** grain " so often observed on planks of wood will 

 come into view, and it will be noticed that the lines 

 . ' B 2 



