310 THE THEORIES OF EVOLUTION 1 



important factor in determining their ultimate des- 

 tiny. 



Korshinsky's theory is not based upon any very 

 large amount of personal experimentation and obser- 

 vation and it is probably for this reason that it has 

 failed to attract as much attention as De Vries' theory, 

 very similar, but based on solid facts and more sys- 

 tematically developed. 



De Vries' system is the result of many years' experi- 

 menting on transplanted wild plants and on various 

 cultivated plants in the botanical gardens of the Uni- 

 versity of Amsterdam. It was in 1886 that De Vries 

 began his experiments and he waited until 1901 before 

 making his conclusions known to the public. De Vries 

 considers that the experimental method is much more 

 important in biology than accidental observation. 

 "Observation usually begins," he writes, "when the 

 mutation has made its appearance; but all conditions 

 previous to mutation are of far higher importance 

 than all those subsequent to it. The parents, grand- 

 parents and previous ancestors must be known indi- 

 vidually." . • • Then experiments may begin. 



The introduction of the experimental method in 

 biology will, he thinks, fill a want which has always 

 been detrimental to the advance of transformist 



1 ( 1 F*£\ S 



"The prevailing belief that slow and gradual, al- 

 most invisible changes constitute the process of evolu- 



