The Origin of Species 323 



species is extremely doubtful, but the clear demon- 

 stration of the nature of these discontinuous varia- 

 tions, and the fact that they do offer a rational 

 explanation for the origin of species, makes the 

 work of De Vries of very great value. 



Criticism of De Vries' Work. The most serious 

 criticism of De Vries' work is the uncertainty of 

 the origin of the species upon which he worked. 

 CEnothera Lamarckiana is not known at present in 

 a wild condition, and Bateson has gone so far as to 

 suggest that it is itself a hybrid, and recent experi- 

 ments by Davis indicate a possible origin of (E. 

 Lamarckiana from a cross of CE. biennis and CE. 

 grandiflora. If such should be the case, Bateson 

 further says that the alleged mutants may be only 

 reversions, or " recessives," in the Mendelian phrase- 

 ology. The occurrence of other similar mutants, 

 which are certainly not of hybrid origin, however, 

 and which are capable of breeding true, would indi- 

 cate that the mutants of De Vries are not merely 

 recessive hybrids. 



Lotsy, in the work already referred to, suggests 

 a very probable cause for the origin of mutants 

 which does not involve the idea of special " inheri- 

 tance units." His view is that the tendency to muta- 

 tion does not lie in the egg-cell, or sperm, but arises 

 subsequent to fertilization as the result of the mating 

 of the most dissimilar gametes, which would nat- 

 urally only occur rarely. 



