ORIGIN OF SPECIES' 95 



as many red campions as there were last summer, nor 

 will there be three thousand times as many more in the 

 succeeding season. The roe of a cod contains sometimes 

 nearly ten million eggs ; but supposing each of these 

 produced a young fish which arrived at maturity, the 

 whole sea would immediately become a solid mass of 

 closely packed codfish. Linnasus reckoned that if an 

 annual plant had two seeds, each of which produced two 

 seedlings in the succeeding season, and so on continually, 

 in twenty years their progeny would amount to a million 

 plants. A struggle for existence necessarily results 

 from this universal tendency of animals and plants to 

 increase faster than the means of subsistence, whether 

 those means be food, as in the first case, or carbonic 

 acid, water, and sunshine as in the second. Animals 

 are all perpetually battling with one another for the 

 food- supply of the moment ; plants are perpetually bat- 

 tling with one another for their share of the soil, the 

 rainfall, and the sunshine. 



The case of the plant is a very important one to 

 understand in this connection, because it is probable 

 that most people greatly misunderstand the biological 

 meaning of the phrase ' struggle for existence.' They 

 imagine that the struggle is chiefly conducted between 

 different species, whereas in reality it is chiefly conducted 

 between members of the same species. It is not so 

 much the battle between the tiger and the antelope, 

 between the wolf and the bison, between the snake 

 and the bird, that ultimately results in natural selection 

 or survival of the fittest, as the struggle between tiger 

 and tiger, between bison and bison, between snake and 

 snake, between antelope and antelope. A human 



