378 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



" Forests, Woods, and Trees in Relation to Hygiene." By Augustine Henry, 

 M.A., F.L.S., &c. 8vo. 314 pp. (Constable, London, 1919.) 18s. net. 



Whether from a purely hygienic or from a commercial point of view, the 

 afforestation of some of the water catchment areas of our country, which ex- 

 tend to fully 920,000 acres, is to be recommended, and will be sufficient reason 

 for devoting fully three-fourths of this book to that important subject. 

 Having, both in Wales and Scotland, had to deal with some of these catchment 

 lands, wc can fully substantiate the author's remarks which are clearly ex- 

 pressed, and we may rest assured that the tree-planting schemes which have been 

 so successfully carried out by the Corporations of Liverpool, Manchester, and 

 Birmingham are but precursors of other and more extensive works of the kind 

 that are soon to follow. 



As not a few of these watershed areas are on exposed, rough grounds at high 

 altitudes, great care in the choice of suitable trees is necessary and several failures 

 in the way of getting plantations established on such sites are directly due to 

 want of discrimination in the species that were used. Some of those recom- 

 mended in this book, such as Abies nobilis (the hemlock spruce), and Cupressns 

 macrocarpa are only to be trusted in the most favoured situations ; and even 

 the Douglas fir we have found unsuited for wind-swept grounds, where it quickly 

 loses its leading shoot and presents a meagre, miserable appearance. For 

 sheltered dips it is a capital tree and grows rapidly, as at Cochwillan plantation, 

 on Lord Penrhyn's estate at Bangor, where it is not however a pure crop, but 

 was only added to fill up blanks in an old oak-wood. That ring or cup shake 

 in Spanish Chestnut timber is due more to wind and less to frost is a generally 

 accepted fact ; while the most important uses to which hornbeam timber 

 is applied are not included in dealing with the wood of that tree. The state- 

 ment that ash can rarely be grown in a wood by itself requires some qualifying, 

 as in Beds and Bucks some of the most profitable plantations are composed 

 of pure ash. 



The afforestation of pit -mounds is a valuable chapter that deserves re-reading, 

 and the work of the Midland Re- Afforestation Association cannot be over-valued 

 in its dealings with these barren and unsightly waste-heaps. 



No less interesting is the chapter on Trees in Towns, though the author's 

 note that the injurious effects of oiling and tarring the roads is not established 

 hardly agrees with the observations of the reviewer and others who have studied 

 the question in London and other large towns. 



That Paulownia imperialis is unlikely ever to succeed in our towns is hardly 

 supported by the magnificent specimen in Regent's Park, or that in the grounds 

 of the Royal Botanic Society. Strange that the Turkey oak is not included 

 amongst other members of its family, as it is by far the most dependable 

 in London, where many giant specimens may be seen ; neither is the Austrian 

 or Corsican pine the best conifer for smoky towns, both being out-rivalled in 

 that respect by the Eastern Thuya and Prumnopitys elegans, while the Maiden- 

 hair tree has reached a goodly size in the foul air of Commercial Road. 



Regarding the hybrid origin of the London plane about 260 years ago, we 

 hope Professor Henry's remarks will not be taken too seriously. The advice 

 on pruning town trees is sound and should be acted on, for. as the author wisely 

 says, " the spectacle of untrained men going about hacking trees in towns is 

 a painful but common one," and nowhere is this more in evidence than in the 

 streets and squares of the great metropolis. 



The sanitary influence of forests can hardly be overrated and is fully explained 

 in the chapter under that heading, while *' Parks in Towns and Municipal Forests " 

 gives a brief but interesting account of the open spaces that have contributed 

 so greatly in the matter of public hygiene. 



Altogether " Forests, Woods, and Trees," which is divided into twelve chapters 

 with forty-nine illustrations and extends to fully 300 pages, will be found an 

 interesting and valuable addition to our forest literature. 



" The Simple Carbohydrates and Glucosides." By E. Frankland Armstrong. 

 Ed. 3. 8vo. x + 2 39 PP- (Longmans, Green & Co. London, 1919.) 12s. net. 



No substances are more important than the carbohydrates in relation to the 

 vital processes of the plant. They form the organic raw-material from which 

 the plant derives the energy required for these processes and from which, together 

 with the materials absorbed by the roots, it builds up in the laboratories of its 

 cells the manifold constituents of its tissues. Moreover, the glucosides, which 

 at one time were regarded as little more than waste or excretory products, are 

 now constantly gaining in the importance attached to them, and there is little 



