LECTUEE XV 



DOUBLE ADAPTATIONS 



The chief object of all experimentation is to 

 obtain explanations of natural phenomena. 

 Experiments are a repetition of things occur- 

 ring in nature with the conditions so guarded 

 and so closely followed that it is possible to 

 make a clear analysis of facts and their 

 causes, it being rightfully assumed that the laws 

 are the same in both cases. 



Experiments on heredity and the experience 

 of the breeder find their analogy in the succes- 

 sion of generations in the wild state. The sta- 

 bility of elementary species and of retrograde 

 varieties is quite the same under both condi- 

 tions. Progression and retrogression are nar- 

 rowly linked everywhere, and the same laws 

 govern the abundance of forms in cultivated 

 and in wild plants. 



Elementary species and retrograde varieties 

 are easily recognizable. Ever-sporting varie- 

 ties on the contrary are far less obvious, and 

 in many cases their hereditary relations have 



430 



