30 Forestry Quarterly. 



and their life history as well as that of his friends who help him 

 keep down the pests. Forest entomology, the knowledge of the 

 insects preying on forest growth and the means of combating 

 them, is, therefore, a well developed branch of general entomol- 

 ogy. Nevertheless a mere modicum of knowledge will suffice, 

 by no means comparable with the requirement in the branches 

 mentioned before. 



Since, however, forests are the harborers of game and forest 

 waters of fishes, a knowledge of game and fish and their life 

 habits may become not only of natural interest but of practical 

 utility and hence claim some attention. 



Finally it may be proper to point out that the aim in the study 

 of natural history by the forester should be rather to secure a 

 general intelligence of nature in its relationships than a mere 

 agglomerated knowledge of unrelated facts and forms. 



Now, turning to the other side of forestry, namely, the busi- 

 ness side, there are two branches which contribute towards 

 building out the subject of forest economy or "forest regula- 

 tion," namely, mathematics and political economy. There is 

 needed a certain amount of mathematical instinct, if not elab- 

 orate knowledge, to understand the relationships of the laws of 

 accretion. 



To measure the quantity of production, which must form the 

 basis of business calculations, a more elaborate use of, and fa- 

 miliarity with, mathematical operations is necessary: forest men- 

 suration has, therefore, developed into a special branch of mathe- 

 matics and many methods have been developed by which not only 

 the volume of the single tree, but the volume and rate of growth 

 of whole stands or acres of trees can be more or less accurately 

 determined. 



One of the most important mathematical problems for the for- 

 ester to settle is, when his crop is ripe. This is not as with agri- 

 cultural crops and fruits determined by a natural period, but by 

 the judgment of the harvester based upon mathematical calcu- 

 lations. There are various principles which may be followed in 

 determining the maturity of a stand or in determining what is 

 technically called the rotation, that is the time within which a 

 forest managed as a unit shall be cut over and reproduced. Either 

 the largest average volume production, or the largest average 



