6 THE PHILOSOPHY OP PRUNING 



however, that I do not propose to discuss me- 

 chanical injuries to the trees, as a result of 

 wounds, for we all know that such injuries are a 

 result of careless or injudicious pruning. My 

 proposition is this: Does it injure a plant to 

 remove a part of it! Is the entire growth of a 

 plant necessary to its health and longevity? 



1. The argument from philosophy. There is 

 an intense struggle for existence among all or- 

 ganisms. The world is now full, and there can 

 probably be no permanent increase in the sum 

 total of animals and plants. If one species in- 

 creases, another must decrease. Changes in the 

 numbers of individuals are, therefore, largely 

 matters of readjustment between different types. 

 Each kind is held down to a certain equilibrium 

 in relation to other kinds. It is easy to see that 

 any species of animal or plant could completely 

 occupy the surface of the globe, if it could mul- 

 tiply to the full extent of its powers. Not only 

 do some species compete with others, but the 

 individuals of the same species compete with each 

 other for standing room. The greater the num- 

 ber of thistles in a given field, the less is the 

 opportunity for another thistle plant to gain a 

 foothold. Now, a tree is essentially a collection 

 or colony of individual plants. Every branch, 

 even every joint of the branch, is endeavoring to 

 do what every other branch does to bear leaves, 

 flowers and seeds. Every branch competes with 



