2dO The Pedigree Faniilies. 



three times, and of forms which have appeared as fre- 

 quently as have 0. albida, 0. ohlonga, O. rubrinervis and 

 O. nan el I a. 



The point cannot be decided in tlie case of O. laevi- 

 folia or O. brevistylis, both of which were found on the 

 spot where O. Lamarckiana was originahy discovered, 

 but have not arisen in my cuhures. Both these, when 

 self-fertihzed, come perfectly true from seed. O. hrevi- 

 stylis breeds true in spite of its small fruits which some- 

 times set no more than a solitary seed. Indeed I thought 

 at first that these fruits were absolutely sterile. 



Oenothera scintillans and 0. lata are exceptions to 

 this rule. The seeds borne by self-fertilized plants of 

 the first named form produce a generation only about 

 one-third of which is 0. scintillans. This is true of the 

 seeds of three distinct individuals which have arisen 

 quite independently of one another. From the seed of 

 a fourth individual however 69 % of O. scintillans were 

 raised ; and these again in the next generation gave from 

 60 to 90 %.i 



This constancy of the new species is an extremely 

 important characteristic. It has enabled O. laez'i folia 

 and 0. brez'istylis to maintain themselves in the spot 

 where they arose — mere scattered examples among the 

 host of Laniarckianas which surround them ; and, what 

 is more, pure in respect of all their characters (apart of 

 course from accidental crossing) 



That the struggle for existence is a pretty keen one 

 in the field in question may be gathered from the fact 

 that a vigorous Lamarckiana can bear 1 00 fruits and that 

 each fruit contains between 200 and 300 seeds. The whole 



^ For further information on this point see section 19 of this 

 part. 



