I. THE PEDIGREE FAMILIES. 



§ I. OENOTHERA LAMARCKIANA, A MUTATING PLANT. 



(plate I.) 



The chief obstacle in the way of getting material suit- 

 able for investigating the origin of species is our complete 

 ignorance of the conditions under which this process 

 takes place. In order to obtain this material I started in 

 1886, to search the country round Amsterdam for spe- 

 cies, exhibiting such monstrosities or other peculiarities 

 as I thought would suit my purpose. As a result of my 

 quest I brought over one hundred species into cultivation, 

 but only one of these turned out to be what I really 

 wanted. 



From this I conclude that most of the species in this 

 locality are passing through a period of non-mutation, 

 and that plants which happen to be actually passing 

 through a mutable phase are encountered at any rate, 

 relatively rarely. 



The plant in question is Oenothera Lamarckiana, 

 which together with its nearest allies O. biennis and O. 

 nitiricafa have been introduced into Europe from Amer- 

 ica. The species Lamarckiana differs from the others 

 by its taller growth, by its much larger and more beauti- 

 ful flowers, by the fact that self-fertilization rarely oc- 

 curs, bv its different leaves, and so forth. ^ O. La- 



^ For the synonyms, and a discussion of the relationship as well 

 as for a more detailed account of its origin see Sur Vintroduction dc 



