REVIEWS 717 



of formed wood can take place only due to activity of plastic material 

 on both convex and concave sides, and recognizes as such the living 

 wood parenchyma which accompanies wood fibers and forms the pith 

 rays, and which is connected with the cambium and younger wood. 

 This accounts also for the more ready response of the broadleaf trees, 

 which are more fully provided with this plastic material. In propor- 

 tion to the presence of these living cells tropistical movements become 

 possible in response to gravity (geotropism) and light (heliotropism). 



B. E. F. 



Western Yclloiv Pine in Oregon. By Thornton T. Munger. Bulle- 

 tin No. 418. U. S. Dept. of Agriculture, Forest Service. February, 

 1917. 48 pp. 



Statistics showing the relative importance of western yellow pine as 

 a commercial timber tree, with particular reference to Oregon condi- 

 tions, are given in the opening pages. Yellow pine covers more area 

 in the State than does Douglas fir, but owing to its lighter yield per 

 acre (7,000 board feet) has only 25 per cent as much volume. As 

 indicated by a map giving the commercial and botanical ranges of yel- 

 low pine in Oregon, the tree is restricted commercially to the region 

 east of the Cascades, except in the southwestern corner, where it is 

 found on the Siskiyou Mountains and west slope of the Cascades. 

 Munger divides the commercial range into three sections : 



Acres of commercial Total stand in thou- 



yellowpine. sands of feet b. m. 



Blue Mountains 4,276,000 31,350,000 



East Slope Cascades 3,400,000 33,185,000 



Southwest Oregon 2,330,000 6,830,000 



Total 10,006,000 71,365,000 



Of these totals, approximately 4,448,026 acres and 34,812,400.000 

 feet board measure are privately owned, while 5,543,480 acres and 

 36,489,700,000 feet board measure belong to the Government.^ Several 

 pages are devoted to paragraphs on "descriptions,"- climate, soil and 

 soil moisture, light, seed production, germination and development of 

 seedlings. Seedlings are found most abundantly "on the exposed spots 

 in the forest, such as on scabby ridges, where the mineral soil is naked. 

 Here germination may be the best, but the mortality of the seedlings 

 the first year is the largest." . . . "The seedlings that ultimately 



'Includes timber on two Indian Reservations and a small amount (UviumI iiy 

 the State. 



'■'Deals witii size, form, root-system, character of the tree, etc. 



