VII.] PLANTS FORCED TO GROW SINGLY. 189 



A meadow may be full of timothy, and grow white clo- 

 ver in the bottom. These diiferences in habits and 

 requirements between different organisms are styled 

 divergence of character by Darwin, and the more dissim- 

 ilar the organisms, within certain bounds, the greater 

 the number which can live together peaceably. Conse- 

 quently, the foreign or remote species, being different 

 from our own, find places not occupied, and they make 

 the most of them. The same is true to a less degree of 

 any organisms which find themselves in new surround- 

 ings. The new enemies come because they see a busi- 

 ness opening : there is little competition. 



A most interesting result of the struggle for 

 existence, and one which I do not remember to have 

 seen stated, is that it forces plants to grow as single 

 and detached specimens, not as clumps nor in colonies. 

 How true this is for herbs and bushes will be appar- 

 ent to anyone who recalls how the common plants 

 grow in great solid clumps in gardens, whilst in the 

 adjacent fields and woods they are scattered here and 

 there as small, and usually slender or dwarf speci- 

 mens. It may be assumed that it is the natural dis- 

 position of all plants to occupy the ground continu- 

 ously and to branch profusely from the base. When 

 they are scattered thinly over any area, it is proof 

 that there are other contestants for the space ; and 

 the tendency for trees and other plants to grow to a 

 single trunk is in consequence, also, of the struggle 

 for a place in which to live. 



I have now said that our enemies increase because 

 cultivation induces change of habits in wild organisms, 

 because it presents an ever -increasing variety of food- 

 or host -plants, because the food supply is large and in 



