50 THS STSVaaLB 70B zxistenck. 



afford spreading room for a larger number of dividuals of mixed 

 species possessing different root-systems than of individuals be- 

 longing to species possessing a similar root-system. Hence the 

 inabiKty of individuals of any species to live under an open or 

 even fairly dense canopy of another species is not necessarily an 

 indication of their not being able to stand the existing amount of 

 shade, for it may be entirely due to there not being room enough in 

 the soil for them owing to both species possessing a similar spread 

 and arrangement of roots, See also footnote on page 29, 



VI. Advanoing age. — =This condition is que of very great mo-: 

 ment in deciding the struggle for existence, since advancing age 

 affects directly the action of rnost of the other conditions. How- 

 it does so, has been indicated in the separate discussion of each 

 of those conditions, sq that to reconsider the various points 

 here would involve needless repetition of a very large portion of 

 the present section, The student is also referred to the discussion 

 of this condition in the First Case for the extent to which jvdvan- 

 cing age may change the relative fitness of individuals of one and 

 the same species. Here we need only add,]5rstly, that the struggle 

 between species and species does nqt begin until one of them 

 is estabhshed or has begiin tp push up ahead, sijch species gain- 

 ing thereby an enormous advantage ; secondly, that later on it is the 

 individuals of species that enter earhest the phs^se of rapid lateral 

 extension which tend to drive out their neigljbours ; and thirdly 

 and lastly, that the victory is ultimately for individuals of that 

 species whose phase of rapid lateral extension is prolonged beyond 

 that of the rest, 



VII. Eelative longevity.— This factor has a most important 

 influence on the struggle for existence, That influence is so great 

 that of itself it enables a species, placed at a disadvantage in most 

 other respects, to prevail in the end. The best instance of this 

 is offered by the teak, which, in spite of every kind of ill-treat- 

 ment, and of an unsuitable soil and cUmate, is able to form extensive 

 copses on the dry barren hills of the Sathpuras and So^thern Vin- 

 dhyas. In the same way, the sal, although gregarious and (ast- 

 growing species like the Tetrantlieras, bamboos, &c. may gain the 

 upper hand of it at first, still fives long enough to see them disap- 

 pear and leave it in complete possession of the ground. Indeed 

 the greater longevity of the more valuable species seems to be a 

 special dispensation of nature, otherwise useless or inferior kinds, 

 like the Cochlospermum Oossypium, Kydia calycina, Helicterei 



