292 BOARD OF AGRICULTURE. [Pub. Doc. 



mission to perform. They must do their part in preventing 

 too great an increase of the wood-eating beetles, and so pro- 

 tect the young pines springing up among the ruins where 

 the forest that is to be is rising from the bones of its 

 progenitors. 



Years roll away, and a new forest waves its branches 

 where the old trees once stood. All that remains of the old 

 now is a great trunk, forming a natural bridge across the 

 stream. Huge and moss-covered it lies, a relic of the past. 

 Along its upper surface runs a well-beaten path, traversed 

 by the shuffling bear, the slinking wolf or the timid deer, 

 descendants, it may be, of the animals who were sheltered by 

 its branches in their prime. 



But, you say, what is the practical bearing of all the fore- 

 going? What the utility of the observations nlade? Know, 

 then, that we cannot study the relations of the creature to its 

 environment without learning something of the great plan 

 governing all. We cannot enter upon the consideration of 

 any of the forces which regulate the increase of animal or 

 vegetable life without being brought face to face with the 

 great laws by which the balance of nature is preserved. 

 How beautiful and yet how complex is this great plan, by 

 which each species of plant or animal fits into the proper 

 place just so long as it serves a useful purpose, then filling a 

 subordinate place, and becoming extinct when its mission on 

 this earth is ended. 



Were there no law regulating the increase of the pine, it 

 would be but a few centuries ere the whole earth would be 

 covered with pines. In such a case there could, of course, 

 be no wood-eating borers and no birds to feed upon such 

 insects ; there could be no grass-eating animals, for there 

 would be no grass. Man himself could not exist. 



Wood-eating insects are no doubt a necessity and are use- 

 ful, when properly held in check by the birds which feed on 

 those insects. If a single species of insect were allowed to 

 go unchecked, it would be but a few years before all the 

 foliage upon the continent would be destroyed. Kirkland 

 has figured that the unchecked increase of the gypsy moth 

 ( Porthetria dispar) would in eight years destroy all foliage 

 in the United States. It is easily demonstrable that certain 



