30 INBREEDING? AND OUTBREEDING 



was the protection of the young. In certain particulars, 

 however, the higher plants did not simulate the higher 

 animals in their reproductive evolution, and it is not diffi- 

 cult to see the reason for the divergencies. Plants re- 

 tained asexual reproduction as an alternative method of 

 propagation, and made a success of hermaphroditism. 

 The obvious necessity for both was their fixed condition, 

 their slavery to the soil ; but if hermaphroditism with its 

 simplest implication, self-fertilization, had become domi- 



Fia. 7. Adaptation for self-pollination by means of spiral twistings of stamens and style. 



(After Kerner.) 



nant, there would have been little from their life histories 

 upon which to base an argument regarding the respective 

 virtues and defects of inbreeding and outbreeding. This, 

 however, was not the case. Many plants characterized by 

 autogamy persisted and flourished. They even developed 

 numerous devices promoting self-fertilization (Fig. 7), 

 such as pollination before the flower opens, inclination 

 of the anthers toward the pistil or the pistil toward the 

 anthers, rapid elongation of the pistil through a ring of 

 stamens, or various torsions of the accessory floral parts ; 

 but it seems perfectly clear from the exhaustive investi- 

 gations on the fecundation of plants made in recent years 



