V. 



NEGATIVE EVIDENCE. 



IT would naturally be expected, from Dar- 

 win's clear notions of evidence in gen- 

 eral, and the necessity that he was under all 

 his life of handling vast bodies of complicated 

 evidence, that his work would furnish examples 

 for the treatment of negative evidence. His 

 estimate of its value is well shown by his treat- 

 ment of the question whether Primula veris, 

 P. vttlgaris, and P. elatior are different forms 

 of the same species. 1 After discussing the 

 evidence in favor of this view he said, " Nega- 

 tive evidence is of little value; but the follow- 

 ing facts may be worth giving." Then follows 

 the recital of his efforts to determine whether 

 the cowslip varies enough to justify the belief. 

 He transplanted cowslips from the fields into a 

 shrubbery, and then into highly-manured land; 

 the next year they were protected from insects, 

 artificially fertilized, and seed grown, which 



1 Different Forms of Flowers on Plants of the same 

 Species, p. 62. 



