PROBLEMS OF MODERN SCIENCE 



its time and published in the obscure Verhande- 

 lungen of the Briinn Natural History Society in 

 1866, lay unrecognised until the principle was 

 rediscovered at the end of the nineteenth century. 



The effect on biology of this rediscovery, and 

 of the publication of de Vries' Mutation Theory, 

 which began in the following year, was dramatic 

 in the extreme. If these results were true, then 

 it appeared at the time that all the neo-Darwinian 

 conceptions of evolution by the slow and gradual 

 accumulation of imperceptibly small variations were 

 swept away. Later developments have brought 

 these results into a truer perspective in relation 

 to Darwin's views, but the first impact of the 

 new conception was sufficiently startling. Small 

 wonder, then, if to a biologist taking up research 

 in these first five years of the century, it seemed 

 that to be young was very heaven. Biology re- 

 ceived an impetus to new development such as 

 physics had received some five years earlier. Under 

 the influence of de Vries on the Continent and 

 Bateson in this country, mutation and Mendelism 

 became the watchwords of the hour. 



To de Vries belongs the credit of introducing 

 the method of experimental breeding into modern 

 biology. The mutation theory of evolution, which 

 postulated the sudden origin of new species and 

 varieties, was based upon some twenty-five years' 

 breeding experiments with evening primroses 

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