THE ORIGIN OF NEW FORMS 



193 



That all ecads will do so upon being returned to the original habitat 

 can not be told until each one has been placed under experiment. 

 This appears to be probable, but preliminary results indicate 

 that the longer an ecad remains in the habitat that produced it 

 the more difficult a change becomes. This is in accord with the 

 general opinion that stability is merely fixed habit. Hence the 

 longer a plant is in the habit of carrying on its functions or pro- 



L 



Fig. 67. The sun form of the mountain skullcap, ScuteUaria hrittonii, and 

 the new form which arises from it by adaptation to deep shade. 



ducing its structures in a certain way the more stable it becomes. 

 In nature ecads are frequent, occurring more or less conmionly 

 wherever distinct formations touch each other. While they may 

 wander back at any time to the original home and revert, they 

 ordinarily persist for years, often doubtless for centuries, as distinct 

 new forms. In amount of difference they are as distinct as many 

 new species and have often been described as such. Whether they 



