MAKING NEW KINDS OF PLANTS 443 



either in the garden or in nature; all selection can 

 do is to temporarily intensify the ' selected character 

 and increase the frequency of its occurrence: when 

 selection ceases the percentage of frequency soon falls 

 to the original figure and all becomes as it was 

 before. Moreover, new species are not formed gradu- 

 ally, as the selection theory demands, but they originate 

 suddenly, fully formed and constant from the start, 

 without any intermediates between them and their 

 parent -species. As there are no intermediate forms, 

 it is useless to search for such "missing links," for 

 .they never existed. This mode of origin of species, 

 which he calls mutation, he has observed year after 

 year in his garden at the University of Amsterdam. 

 It occurs in one of the Evening Primroses ((Enothera 

 LamarcJciana, or Lamarck's Evening Primrose, Figs. 

 247 to 250), which each year produces several new 

 species. These remain constant and perfectly distinct, 

 and never produce intermediates between themselves 

 and their parent -species. They originate without any 

 of the means ordinarily considered necessary: no ex- 

 tended lapse of time is demanded;- no fluctuating 

 variation, crossing or struggle for existence appear to 

 enter directly into the matter. 



It is not to be supposed that this process can be 

 observed in the majority of plants. The opponents of 

 Darwin have already contended, on the ground of care- 

 ful experimental evidence, that species, instead of 



