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always to regain its eouililiriuni when it has been upset. In 

 support of the latter statement there may be cited the case of those 

 predatory animals which depend for their subsistence, either direct- 

 ly or indirectly, on mice or rabbits, and which show a fairly regular 

 periodic fluctuation in numbers, that can be correlated with the 

 abundance of their food supply. ' ' It is not an uncommon observa- 

 tion that an unusual increase in mice or small rodents often brings 

 a flight of owls to the vicinity to feed on them until they are 

 redneecl in numbers and no longer obnoxious.' ' Forbes ' likens 

 these interrelations to a series of expanding and contracting 

 springs, each of which in expanding is checked, pushed back, or 

 compressed by the others. The moment one weakens, and becomes 

 slightly contracted, others expand to fill the vacancy. When one 

 expands unduly, others exert increased force to contract it again. 

 It is possible to aid and even to control nature in this work 

 of regaining the desirable balance which man is forever destroying. 

 The methods suggested below are an attempt to work with natural 

 laws rather than against them, to the end that a maximum harvest 

 of all forest products may be obtained with a minimum of distur- 

 bance to the orderly system of nature. 



The Practice of Forestry in Relation to 

 Wild Life Oonservatiop and Recreational Use. 



Forestry is the science and art of managing forests in con- 

 tinuity for forest purposes. It is not confined merely to the pro- 



