CHAPTER VII. 



THE BATTLE OF LIFE. 



Plants considered in their relation to their struggle for existence. Effect 

 of adverse external conditions. Hostility of rivals, Weeds. Competi- 

 tion of fellows. Gregarious vegetation. Associated or mixed vegeta- 

 tion. Alternate vegetation, rotation. Objects of the cultivator not 

 the same as those of the plant under natural circumstances. The 

 battle as studied in pasture-land or meadow. The grass-plots at 

 Rothamsted their botanical composition and the way they are affected 

 by manures of different kinds. The Grasses, their nature and dif- 

 ferences ; contrasts between nearly allied species. Th Leguminosae. 

 The Miscellaneous weeds. The vegetation and characteristics of the 

 continuously unmanured plot. The effects of different manures and 

 of different combinations of manures upon the struggle. Effects of 

 disuse of manure, and of the substitution of one kind for another. 

 General results. 



IN former sections mention has been made of the rela- 

 tions which the living plant bears to the heat, light, 

 moisture, and other physical conditions, by which it is 

 surrounded. These conditions are sometimes favourable, 

 sometimes prejudicial. In the latter case, the existence of 

 the plant becomes a prolonged struggle against adverse 

 influences. To a certain extent it is always so, and when 

 the difficulties can no longer be counterbalanced or over- 

 come, plants, like other living beings, succumb and die. 

 The life of each individual then may be described as a 

 battle against circumstances. 



But apart from this external conflict with the elements, 



