90 THE BIOC08M08 PRELIMINARY. 



by destruction. Plants likewise have the 

 same prolific energy in tapping the general 

 source of vitality that they seem able to ab- 

 sorb it if not halted in their reproduction. It 

 would appear that each living species has the 

 bent to take the whole Earth-life as its own 

 for its kind. Moreover, all living things, 

 plant and animal, must have food, whose sup- 

 ply is limited ; the individuals of the same spe- 

 cies would at last fall into conflict over suste- 

 nance. The surface of the globe would soon 

 be too small for the exploitation of any vig- 

 orous species in the matter of propagation 

 and subsistence. 



Thus the Earth-life in its totality has its 

 bounds; though it includes all individual 

 plants and animals, it too is an individual. 

 Within it each living thing arises and passes 

 away ; has it the same destiny? That is again 

 the problem of the extinction of our globe, 

 which springs upon us in these scientific days 

 from many sides. The Earth-life is still going 

 on, youthful, it may be, but more probably in 

 its middle age the only individual of its sort 

 in the universe. Herein it differs from all veg- 

 etal and animal existence, and of course from 

 us. A thousand years of Earth-life is hardly 

 a day, in comparison with our lives. What 

 its vital round may be, and how long it will 

 last, can only be guessed. What, however, is 



