432 JOURNAL OF FORESTRY 



the several lines under which each has been developed. Although the 

 author goes into considerable detail in describing each of the above 

 methods he draws no conclusions as to which method is the best in 

 measuring the sun's radiation with particular objects in view. For 

 instance he gives no clue as to the best method for measuring solar 

 radiation in order to ascertain its effect upon living vegetation. 



J. W. T. 



Pulling, Howard E. Sunlight and Its Measurement. The Plant World, Vol. 

 XX, Nos. 7 and 8, pp. 151-171 and 187-209. 



SILVICULTURE, PROTECTION, AND EXTENSION 



The biological method of combating insect 

 Applied pests (by favoring the development of their nat- 



Entomology ural enemies) was first suggested to the author in 

 in America connection with ravages of the gypsy (Lymantria 

 dispar L.) and the brown-tail moths (Buproctis 

 chrysorrhoea L) and the oak caterpillar {Cnethocampa processiona, L.) 

 on the south slopes of the Transylvanian Alps in Roumania in 1887, 

 and in Croato-Slavonia and Bosnia in 1889. This method has been 

 developed on an extensive scale in the United States, under the leader- 

 ship of the Bureau of Entomology (a number of instances are given) 

 and other methods have also been widely studied, especially the use of 

 chemicals. The success of American entomologists in this work, which 

 requires a very thorough detailed knowledge of the insects, their life 

 habits, and their enemies, is attributed to their capacity for going 

 deeply and thoroughly into a study and to their adaptation to observa- 

 tional investigation of practical value, but primarily to the organiza- 

 tion of entomological research activity, with its division of work among 

 specialists, and its centralization or correlation by a central agency at 

 Washington. Prof. Escherich has been striving for development along 

 similar lines in Germany, through his Society for Applied Entomology 

 and his Zeitschrift fur Angewandte Entomologie, and has laid the be- 

 ginnings of a Research Institute in Munich, to study methods of com- 

 bating insect pests injurious to farms, forests, and farm and forest 

 products and articles made from them, as well as to domestic animals 

 and human beings. The Institute is to be exclusively for research, not 

 for instruction, but is to publish its results in language that can be 

 understood by practical farmers, foresters, and manufacturers. Esche- 



