SUMMARY OF EVIDENCE 85 



Now the natural development of species is either a 

 long-drawn-out process or a comparatively rare event, 

 whatever may be the true description of the method of 

 evolution. If the Darwinian description is correct, the 

 development of one independent species from another 

 must consume a much longer period of time than has 

 elapsed since men have begun to investigate the process. 

 If, on the other hand, the mutations theory of de Vries 

 is to be accepted, the origin of a new species, sudden 

 though it be, must occur at rare intervals — too rare 

 for the observance of many instances within the brief 

 time that has gone by since men have taken intelligent 

 notice of biological phenomena. The conclusion to 

 which we are driven is that we ought not to expect to 

 obtain much or conclusive direct evidence of the natural 

 evolution of species. This being the case, we ought 

 not to permit the comparative inadequacy of such e\d- 

 dence to blind our minds to the large amount and con- 

 vincing quality of the indirect evidence which I have 

 been briefly explaining. With such preliminary cau- 

 tions in mind, I now ask you to consider what direct 

 evidence has in fact been obtained. Such as it is, this 

 evidence is favourable to the evolutionary hypothesis. 

 No direct evidence has been advanced to the contrary 

 — at least none which appears to be incapable of being 

 answered and explained on evolutionary grounds. 



8. The alleged direct evidences are those of domesti- 

 cation or artificial selection and of the natural muta- 

 tions which have been investigated by de Vries and 

 others. The facts observed in domestication and 



