LECTURE XX 



THE ORIGIN OP WILD SPECIES AND VARIETIES 



New species and varieties occur from time to 

 time in the wild state. Setting aside all theo- 

 retical conceptions as to the common origin of 

 species at large, the undoubted fact remains that 

 new forms are sometimes met with. In the case 

 of the peloric toad-flax the mutations are so 

 numerous that they seem to be quite regular. 

 The production of new species of evening-prim- 

 roses was observed on the field and afterwards 

 duplicated in the garden. There is no reason 

 to think that these cases are isolated instances. 

 Quite on the contrary they seem to be the pro- 

 totypes of repeated occurrences in nature. 



If this conception is granted, the question at 

 once arises, how are we to deal with analogous 

 cases, when fortune offers them, and what can 

 we expect to learn from them? 



A critical study of the existing evidence seems 

 to be of great importance in order to ascertain 

 the best way of dealing with new facts, and of 

 estimating the value of the factors concerned. 



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