1 86 Changing Plant and Animal Nature 



If we could breed among animals in captivity to yield 

 a new artificial species which is in every respect like the tiger 

 of the Indian jungle, we should have an animal that could 

 not maintain itself adequately in the wilds of Kansas, let us 

 say. Yet this would be in every respect as real a species as 

 the tiger that does maintain itself in Asia, where our artificial 

 species could also live. Our species artificially established 

 may not be fit to live if given its freedom in the neighbor- 

 hood of the laboratory, but may nevertheless adjust itself to 

 a natural environment of another type. The requirement 

 that an artificially produced type, in order to be considered 

 a new species, be able to maintain itself under natural con- 

 ditions may be fair enough; but it is not fair to test such an 

 artificial creation by placing it arbitrarily in any natural 

 environment at random. Nature's own species cannot stand 

 that test. 



The conditions of life include the activities of other 

 living things as well as the physical factors of the environ- 

 ment. Whether a given type of plant or animal is to be re- 

 garded a genuine species or not is a question of its being able 

 to live at all and to perpetuate itself in distinction from other 

 groups. The fact that sooner or later it may become ex- 

 terminated in the struggle for life should have no bearing 

 upon this point, for the history of the world is a constant 

 record of such exterminations. On the American continent 

 there lived and eventually died out millions of years before 

 the arrival of Columbus distinct species of horses and camels, 

 of elephants and monkeys. A change in climate may force 

 a species to migrate to remote regions. Certain insects com- 

 ing out of the ground where they had spent several winters 

 may suddenly find themselves without food supplies and so 

 die out. It is important to these insects that the plants 

 moved away. It does not make them, however, any less 

 " a species " because their food plants have been removed 

 from over their heads and under their feet. A change in the 

 market may lead to the abandonment of potato culture over 

 a large area. Potato beetles coming out of the ground some 



