TEXTBOOK FOE SENIOR STUDENTS 165 



trees, climbing plants, and water-plants, as common biological types. 

 A concluding chapter forms an introduction to the study of plant- 

 associations. 



A new feature of this edition is the addition of a supplement on 

 seedless plants, a series of short chapters in which the structure and 

 life-history of Algae, Fungi, Mosses and Liverworts, and Ferns are 

 illustrated by a few selected types. 



The illustrations are clear and adequate, but the book has been 

 somewhat carelessly produced ; there is no reference on the title-page 

 to the fact that this is a second edition — on the contrary, the back 

 of this page bears the legend " First edition 1915. Keprinted 1919 " ; 

 the pages are not uniform in size and the volume is badly bound. 



A. B. R. 



Our National Forests : a sTiort popular account of the loorlc of the 

 United States Forest Service on the national forests. By 

 R. H. D. Boerker, Ph.D., New York. The Macmillan Co., 1919, 

 pp. Ixix, 238. With 80 illustrations. Price 12s. 6d. 



Manual of Tree Diseases. By W. Howard Rankin, A.B., Ph.D., 

 Assistant Professor of Plant Pathology, New York State College 

 of Agriculture, pp. xx, 398. With 7U Figures. Same publishers 

 and price. 



Those of us who have watched with admiring eyes the progress 

 of State and National forestry in America since Dr. F. B. Hough's 

 memorable European tour of inspection, rather more than forty years 

 ago, can appreciate Dr. Boerker's fully justified pride in his country- 

 men's achievement. The forest statistics of half a continent neces- 

 sarilv deal with large figures. When we read that the United States 

 use annually "90,000,000 cords of firewood, nearly 40,000,000,000 feet 

 of lumber, ] 50,000,000 railroad ties, nearly 1,700,000,000 barrel staves, 

 445,000,000 board feet of veneer, over 135,000,000 sets of barrel 



headings over 3,300,000 cords of native pulpwood, 170,000,000 



cubic feet of round mine timbers, .... and nearly 3,500,000 telephone 

 and telegraph poles," we are not surprised to learn " that out of 5200 

 billion feet of merchantable timber once present, only 2000 billion 

 feet are left." Whilst in Germany, where scientific management has 

 brought about the largest annual increment of the national forests per 

 acre, the annual consumption of wood for all purposes — before the 

 recent dehdcle — was only 40 cubic feet per head of the population, in 

 the United States it was nearly 250 cubic feet ! Naturally, since the 

 destruction of the Apj^alachian forests ** the surrounding country has 

 suffered from alternate floods and droughts ; great manufacturing 

 centres have lost their steady supply of water ; harbours are filled with 

 silt from the mountain sides; and fields, once fertile, are covered with 

 sand, gravel, and debris." Thus America, like other lands, has learnt 

 by bitter experience, and has realised " that forest conservation can be 

 assured only through the public ownership of forest resources." The 

 bulk of the mixed hardwood forests of the Eastern States has gone 

 beyond recall, and the reserves of which Dr. Boerker tells the story are 

 coniferous forests at high altitudes in the mountain ranges of the 



