76 BIOLOGICAL PROBLEMS 



the plant or its offspring, or both, for his own main- 

 tenance, reproduction, and bequeathment. Sometimes 

 the human being is so kindly as to allow the use of 

 the conquered the plant to some animal, but even 

 then, more especially in the case of farm live stock, 

 he has the ulterior motive of self-preservation or of 

 gaining for himself greater ease. This struggle be- 

 tween man and plant may be roughly divided into 

 three stages, all more or less coinciding with various 

 stages in our civilization. The most primitive con- 

 sists in a kind of war carried on by a small numbei 

 of men among an innumerable host of indigenous 

 plants, these few selecting victims here and there on 

 which to prey. Children blackberrying, schoolboys 

 nutting, or their elders truffle-hunting among the 

 beech woods, are among the more elementary ex- 

 amples of this guerrilla warfare; or again this type of 

 war is exemplified by the doings of those picturesque 

 individuals called, in different parts of the world, 

 " ranchmen ", " cowboys ", or " bushmen ", who con- 

 trol vast herds of cattle or sheep on large areas of the 

 little-inhabited parts of the earth's surface. 



A further advance in the evolution of strife consists 

 in the wholesale destruction of living plants to enable 

 man to rob from their offspring the residue left for 

 them in the land by numberless generations of fore- 

 bears. This second stage is well exemplified by the 

 husbandmen of the prairies, whose exploitation of the 

 "virgin " soils of the world is well known to you all. 

 This enterprise is a certain advance in the science of 

 this class of war, it requires some material, a certain 

 amount of preconceived plan, and some systematic 

 endeavour to ensure success. As in the first case, 

 however, its essence likewise consists of theft carried 

 out against plants indigenous to a district, and, the 

 booty once secured, man's role is one of retirement, 



