318 Origin of Each Species Considered Separately. 



sow the seed. Of the whole quantity of seed borne by 

 200 fruits there germinated a httle over 300 seeds. That 

 is 1 to 2 seeds per fruit. The mother plants had grown 

 amongst other kinds and were fertilized by bumblebees 

 and therefore largely crossed. Nevertheless of the 83 

 flowering plants to which this seed gave rise 69 or 83 % 

 were O. hrevistylis. 



This result encouraged me to try artificial self-fertili- 

 zation in parchment bags. For this purpose I chose in 

 1897 those plants whose stigmas projected farthest out 

 of the tubes; for I had satisfied myself that as a rule 

 these furnished the largest fruits. I harvested seeds from 

 five plants. In 1898 I sowed the seed of each plant 

 separately. Nearly all the young plants flowered between 

 August and October; they were all, without exception, 

 short-styled. Altogether there were 175; some in flower 

 and some only with buds, in which, however, I was able 

 to observe the length of the style. 



Oenothera hrevistylis, therefore, when self-fertilized, 

 is absolutely constant in spite of its comparative sterility. 



B. THE CONSTANT NEW SPECIES. 



§ 12. OENOTHERA GIGAS. 



(Plate II.) 



Oenothera gigas is at once the finest and rarest new 

 species that has arisen in my cultures. Whereas most of 

 the new forms are weaker than the parent species this 

 one is almost in every respect stronger and bigger and 

 more heavily built. A comparison of Plates I and II 

 will show at a glance the nature of the difference be- 

 tween gigas and Lamarckiana ; both represent the top of 



