Theories of Evolution 19 



show that he was quite right, and that the 

 cause of the divergence of opinions is due 

 simply to the very incomplete state of knowl- 

 edge concerning both processes. If both are 

 critically analyzed they may be seen to comprise 

 the same factors and further discussion may be 

 limited to the appreciation of the part, which 

 each of them has played in nature and among 

 cultivated plants. 



Both natural and artificial selection are part- 

 ly specific, and partly intra-specific or individ- 

 ual. Nature of course, and intelligent men first 

 chose the best elementary species from among 

 the swarms. In cultivation this is the process of 

 variety-testing. In nature it is the survival of 

 the fittest species, or, as Morgan designates it, 

 the survival of species in the struggle for ex- 

 istence. The species are not changed by this 

 struggle, they are only weighed against each 

 other, the weak being thrown aside. 



Within the chosen elementary species there 

 is also a struggle. It is obvious, that the fluc- 

 tuating variability adapts some to the given 

 circumstances, while it lessens the chances of 

 others. A choice results, and this choice is 

 what is often exclusively called selection, either 

 natural or artificial. In cultivation it produces 

 the improved and the local races ; in nature little 

 is known about improvement in this way, but 



