76 
Lhe present work is divided into two main parts. The first part 
deals with the more important structural and physical properties 
of wood, and includes a general description of a tree, then 
separate descriptions of different parts such as pith, bark, primary 
wood, cambium, vessels, tracheids, wood fibres, wood parenchyma, 
rays, resin ducts, pits, tyloses, pith flecks, growth rings, heart- 
wood and sapwood, the important particulars in each case being 
illustrated by figures of the parts magnified 200-250 diameters. 
Subjects such as grain and texture, knots, density and weight, 
water content, shrinkage, warping and checking, hygroscopicity, 
permeability, conductivity, resonance, colour, lustre, scent and 
taste are also discussed. 
The second part is devoted to a key which includes all the 
important, and some of the unimportant, woods of the United 
States. By means of this key it is possible to place a wood fairly 
correctly in its genus and into a group of species, but, except in 
the case of species with very distinct characters, it does not 
remove the difficulty of the identification of species by means 
of wood characters alone. This is recognised by the author, for 
in his introductory remarks the words occur, “‘in the woods of 
many genera the structural variations apparently are not suffi- 
ciently distinet and constant to assure specific identification. 
knowledge of the botanical and commercial range of each species 
will often serve as a basis for further sub-division of a group in 
specimens. 
_ Following the key is a long bibliography referring to ‘‘ Woods 
in General ”’ and to the “ Uses of the Woods of the United States 
and Canada,’”’ an appendix dealing more fully with various 
features referred to earlier in the work, a good index, and several 
plates showing wood structure. 
_ The volume may be regarded as a very useful addition to the 
literature on the Identification of Woods, and it will be found 
valuable, not alone to students in the United States, but also to 
those in other countries, W.D. 
cultivator has not In recent times been well supplied with up-to- 
date literature in his own special line, offered to him at any rate 
; 
__* The Journal of Pomology. Edited by Edward A. Bunyard, F.L.S. 
Maidstone, George Bunyard & Co., Ltd. Published quarterly. $ 
