1 8 Plant Life and Evolution 



ing in a sun-baked, hard-trodden path ; and yet they 

 will succeed in flowering and maturing their seeds 

 under these adverse conditions. This adaptability 

 of plants and the readiness with which they respond 

 to changes in environment make them especially 

 suited to experiments, and in many ways they are 

 therefore easier to study than are most animals. It 

 is not strange then that they should have been made 

 the subject of many experiments bearing on the 

 question of the factors concerned in organic evolu- 

 tion and the origin of species. 



