FORESTRY. 43 



important pes5ts and diseases of the apple, pear, peacli, plnm, clierry. etc., to- 

 gether with directions for their control and the preparation of spray mixtures. 



FORESTRY. 



Michigan trees. — A handbook of the native and most important intro- 

 duced species, C. H. Otis (Univ. Bui. [Mich.], n. ser., 14 {1913), No. 16, pp. 

 XXXII+246, pi. 1, figs. 62S).—A popular guide to the trees of Michigan, the 

 distinctive feature of which consists of keys which use both summer and winter 

 characters as a basis for identification. 



Note on tapping of Boswellia serrata trees in the Siwalik Division, United 

 Provinces, R. S. Peabson {Indian Forester, 39 {1913), No. J,, pp. 196-199).— 

 Experimental data on the extraction of gum resin from B. serrata trees are 

 given and discussed. 



Investigations on the production of poplar wood and on the extension of 

 the industry {Bui. Mens. Off. Renseig. Agr. [Paris], 12 {1913), No. S, p-p. 

 273-296). — This comprises a survey of the production of poplar wood in various 

 departments of France. 



Mechanical properties of western larch, O. P. M. Goss {U. S. Dept. Agr., 

 Forest Serv. Bvl. 122, pp. IfB, pis. 6, figs. 12). — In continuation of previous in- 

 vestigations of structural timbers (E. S. R., 28. p. 544). results are given of a 

 series of tests to determine the mechanical and physical properties of westeru 

 larch, and the various structural uses of the wood are described. 



Bridge stringers and car sills containing defects commonly found in timber 

 purchased on the market were tested to secure strength values for use in 

 design, to determine the influence of seasoning and of defects on strength, and 

 to compare the efficiency of grading rules and specifications. Small, clear, 

 straight-grained pieces cut from the uninjured portions of the large beams 

 were tested to determine the efi'ect on strength of rate of growth, weight, and 

 moisture. The results of the various tests are tabulated and discussed. 



The composite type on the Apache National Forest, H. H. Gbeenamyke 

 {U. S. Dept. Agr., Forest Serv. Bui. 125, pp. 32, figs. 4).— The study of the 

 above type, the results of which are given in this bulletin, was made in order 

 that a plan of management for it could be included in the working plan for 

 the forest. The type is discussed with reference to its extent and composition, 

 probable history, average stand, economic importance, and future composition. 

 Diameter, height, and volume tables are given for western yellow pine, Douglas 

 fir, and blue spruce, together with comparative form factors and increment, and 

 the comparative growth of western yellow pine in pure and in composite stands. 

 Data are also given showing the effect of cutting on three different reproduction 

 plats. 



A plan of management for the composite type is discussed under the follow- 

 ing general headings : Method of cutting, rotation, brush disposal, fire, and 

 grazing. 



Forestation of the sand hills of Nebraska and Kansas, C. G. Bates and 

 R. G. Pierce {U. 8. Dept. Agr., Forest Serv. Bui. 121, pp. 49, pis. IS, fig. i).— 

 This comprises an account of the work accomplished, principally by the Forest 

 Service, in forestation of the sand hills of Nebraska and Kansas. Both 

 nursery and field planting operations are described in detail with the view of 

 pointing out to planters the mistakes and successes which have been attained by 

 using different methods. 



Jack pine and western yellow pine have been the 2 principal species employed 

 in the Nebraska sand hills. In addition to these, various hardwood species have 

 been used in the Kansas plantings. The species of trees found to be the most 



