FOEESTEY — GRAVES. 261 



ring of growth, together with the new leaves that appear every year, 

 is in reality new colonies of cells. Some of the cells die toward the 

 end of the vegetative season; others continue to live for a number 

 of years. When the conditions of life in a forest have changed for 

 a certain tree, when, for instance, from a dominant tree it became 

 a suppressed one, the new colonies of cells formed during that year, 

 and which sustain the life of that tree, are naturally adapted to these 

 new conditions. The same is true when a suppressed tree, through 

 some accident to its neighbors, comes into full enjoyment of light. 

 The last annual growth is at once capable of taking advantage of 

 the new situation created in the forest. Therefore as long as a tree 

 can form annual rings it possesses the elasticity and adaptability 

 essential for trees living in dense stands. It is only when a tree is 

 suppressed to a point when it can not form new growth that it dies 

 and is eliminated from a stand. 



Because of the fact that the forest is the highest expression of 

 social plant life, the foresters occupy the strategic position from 

 which they command vistas accessible only with difficulty to other 

 naturalists. In this lies the strength of forestry, its peculiar beauty, 

 and the debt which natural science owes to it. It is a significant 

 fact, although, of course, only of historic importance, that, according 

 to Charles Darwin ^ himself, it was " an obscure writer on forest 

 trees " who, in 1830, in Scotland — that is, 29 years before the Origin 

 of Species was published — most expressly and clearly anticipated his 

 views on natural selection in a book on Naval Timber and Arbori- 

 culture. For the same reason it was foresters, who, long before the 

 word "ecology" was coined, had assembled a vast amount of mate- 

 rial on the life of the forest as a plant association — the basis of their 

 silvicultural j^ractice. Warming, Schimper, and other early writers 

 on ecology borrowed most of their proofs and examples from the 

 facts established by the foresters, and the forest literature of to-day 

 is still practically the only one which contains striking examples of 

 the application of ecology to the solution of practical problems. 



One discovery recently made at the Wind River Forest Experi- 

 ment Station, in Oregon, comes particularly to my mind. In north- 

 western Idaho, where the western white pine is at its optimum growth 

 and is greatly in demand by the lumberman, our former method of 

 cutting was to remove the main stand and leave seed trees for the 

 restocking of the ground. In order to protect the seed trees from 

 windfall they were left not singly but in blocks, each covering sev- 

 eral acres. The trees left amounted often to from 10 to 15 per cent 

 in volume of the total stand, and since they could not be utilized 

 later they formed a fairly heavy investment for reforesting the cut- 

 over land. A study of the effect of these blocks of seed trees upon 



1 Origin of Species. 



