60 Fecundity of Organisms. 



able case, consider the elephant, which is the slow 

 est breeder of all known animals. Yet, at the 

 minimum rate of increase, a single pair would 

 &quot; after a period of from seven hundred and forty 

 to seven hundred and fifty years &quot; have &quot; nearly 

 nineteen million&quot; living descendants. &quot;Even 

 slow-breeding man has doubled in twenty-five 

 years, and, at this rate, in less than a thousand 

 years there would literally not be standing- 

 room for his progeny.&quot; Or, consider the case of 

 plants. There is no plant which does not produce 

 more than two seeds ; yet, merely at that rate of 

 increase, an annual plant would, in the course of 

 twenty years, produce a million plants. Without 

 adding examples, we may now realize Darwin s 

 general statement &quot;that every organic being natu 

 rally increases at so high a rate that, if not de 

 stroyed, the earth would soon be covered by the 

 progeny of a single pair.&quot; Hence, as infinitely 

 more individual animals and plants are produced 

 than can possibly survive, nature must be the 

 scene of universal competition. &quot; There must in 

 every case be a struggle for existence, either one 

 individual with another of the same species, or 

 with the individuals of distinct species, or with 

 the physical conditions of life.&quot; Existence is an 

 appalling tragedy, with the universe for its scene, 



