Taxonomic Anomalies 683 



an explanation of this case. It is simply im- 

 possible to imagine the causes that might have 

 produced such a character. The only way out 

 of this difficulty is to assume that it has arisen 

 at once, in its present apparently differentiated 

 and very variable condition, and that, being 

 quite uninjurious and since it does not decrease 

 the fertility of the race, it has never been 

 subjected to natural selection, and so has saved 

 itself from destruction. 



But if we once grant the probability of the 

 origin of the ' ' Nepaul-barley " by a sudden mu- 

 tation, we obviously must assume the same in 

 the case of the Helwingia and other normal in- 

 stances. In this way we gain a further support 

 for our assertion, that even the strangest 

 specific characters may have arisen suddenly. 



After having detailed at some length those 

 proofs which seem to be the most striking, and 

 which had not been previously described with 

 sufficient detail, we may now take a hasty survey 

 of other contingent cases. In the first place the 

 cruciate flowers of some onagraceous plants 

 should be remembered. Small linear petals oc- 

 cur as a specific character in Oenothera cru- 

 ciata of the Adirondacks, but have been seen to 

 arise as sudden mutations in the common even- 

 ing-primrose (0. biennis) in Holland, and in the 

 willow-herb (Epilobium hirsutum) in England. 



