62 Forestry Quarterly. 



A Manual for Northern Woodsmen. By Austin Cary. Har- 

 vard University Publishers, Cambridge, 1909. Pp. 250. Price, 

 $2.00. 



This manual is a very handy book, not only on account of 

 its contents, but also in the make-up. It contains chapters on 

 surveying, mapping, mensuration and estimating. The author 

 does not lay claim to originality for much of the material, but 

 has drawn together what he considers likely to be most useful. 

 The result is a very handy pocket manual of information along 

 the above lines most likely to be called for in woods work. A 

 chapter of tables increases the usefulness of the book. 



It might be suggested that the introduction of a chapter on sil- 

 vicultural questions, rates of growth, etc., would not have been 

 amiss, since the book will no doubt be read by many woodsmen 

 who have no knowledge of forestry principles. 



J. H. W. 



Die Harze und die Harzbehalter mit Einschluss der Milchs'dfte. 

 By Dr. A. Tschirch. 2nd Edition, 1906. 1268 pp. Price, 32Mk. 



This is the most exhaustive work on resins and resin ducts in 

 existence, based on a life time of study, including all the known 

 resins and milky juices of the world. 



The author distinguishes a primary or superficial resinous 

 exudation as a result of superficial injury, and a secondary more 

 vigorous resin flow in the same species as a result of deeper 

 incisions, including a flow richer in turpentine, and including 

 also the formation of resin ducts where normally such are absent, 

 as in firs, so that the wounding is really the cause of the resin 

 formation. Full description of the various resins and balsams and 

 of their commercial collection and use is given. 



Here, however, weaknesses appear. How even a well informed 

 author can go horribly astray is attested by his reference to 

 Abies balsamea and Abies Fraseri as sources of Canada balsam, 

 and Abies Canadensis and Pinus Fraseri are also cited as sources 

 of supply. 



The botanical part undoubtedly is the most interesting, es- 

 pecially as it furnishes a new explanation of the origin of resin 

 formation. The author recognizes an amorphous resinogen layer 

 which surrounds the resin duct, superimposed on the thin walled 



