242 EXPERIMENT STATION EECOED. [Vol.36 



The roses, Cochet-Cochet and S. Mottet (Les Rosier s. Paris: O. Doin & 

 Sons, 1916, 4- ed., rev. and enl., pp. XIV+370, figs. 66). — A revised and slightly 

 enlarged edition of this work (E. S. R., 22, p. 449). 



FORESTRY. 



The book of forestry, P. F. Moon {Neio York and London: D. Appleton & 

 Co., 1916, pp. XVII-\-315, figs. 79). — A popular treatise on forestry prepared 

 with special reference to its use by the general reader, and particularly " Young 

 America." 



Part 1 tells the story of the forest, how it grows, how it is planted, the life 

 of a forester, etc., the subject matter being based on methods and conditions as 

 found in the United States. Part 2 contains popular descriptions of the more 

 important trees and shrubs in each section of the country, including also a key 

 for the identification of the woods of the dii1;erent species. Appended to the 

 work are tables showing the uses of the principal American species, volume 

 table measurements for white pine, a list of reference books on forestry, and 

 definitions of terms used in forestry and logging. 



The mountain communities and the Forest Service, C. DuBois {Univ. Cal. 

 Jour. Agr., 4 {1916), No. 3, pp. 71-74, figs. 3).— In this article the author de- 

 scribes some extension phases of the U. S. Forest Service employees' work 

 among mountain communities. 



Grazing resources of the National Forests, J, T. Jakdine {Univ. Cal. Jour. 

 Agr., 4 {1916), No. 3, pp. 79-81, figs. 3). — An account of the extent and utiliza- 

 tion of the grazing facilities of the National Forests. 



A new method of germinating acorns for forest planting, J. W. Harsh- 

 bergeb {Amer. Forestry, 22 {1916), No. 275, pp. 687, 688, fig. i).— The method 

 here described and illustrated consists in taking immature acorns, the embryos 

 of which have not ceased to grow, and planting them. The result is the elonga- 

 tion and growth of the embryo into a young seedling plant without any inter- 

 vening rest period. 



In view of the trouble in successfully preserving the viability of acorns over 

 winter, it is suggested that the acorns can be planted while green in protected 

 frames and carried over winter in the frame or cool greenhouse already ger- 

 minated and ready to plant out in the spring. 



Studies in tolerance of New England forest trees. — III, Discontinuous 

 light in forests, G. P. Burns {Vermont Sta. Bui. 193 (1916), pp. 3-23, pis. 4).— 

 In continuation of previous studies of tolerance of forest trees (E. S. R., 31, 

 p. 838), the author reviews the literature dealing with light measurements in 

 forests and presents the results of light readings secured from a number of 

 tree zones in Michigan and Vermont. The readings were made with special 

 reference to determining the value of light measurements in the forest and 

 their significance in a study of the light requirements of our forest trees. A 

 bibliography of cited literature is appended. 



Summing up the results of previous investigators relative to light quality, 

 the author concludes that filtered light in the forest has little value as a means 

 of decomposition of carbon dioxid ; the important light in the forest is weakened 

 white light. Data secured from readings in Michigan and Vermont forests 

 show conclusively that the present methods of determining light values in the 

 open forest are of little value inasmuch as the so-called shade of the forests 

 is a discontinuous shade and a constantly changing factor. " The variations in 

 light intensity due to clouds, the impossibility of making equal exposures in 

 repeated readings, the variability of the forest cover thus requiring the operator 

 to choose a typical station for the forest under consideration, and the habit of 



