Oenothera Lata. 



403 



I hold that all the new characters of a mutant are 

 manifestations of a single change that has taken place 

 within it. Morphological proof of this thesis can as yet 

 hardly be produced, but physiologically it follows of 

 necessity, in my opinion, from the fact that these char- 

 acters are always associated and, so far as our experience 

 goes, cannot be separated. 



Fig. 88. Oenothera lata. A lateral branch at the end of 

 August just opening its first flower. 



Oenothera lata is perhaps the most beautiful example. 

 I have already described the characters peculiar to it in 

 § 3 on pages 239-243 (Fig. 46), but I propose now to 

 elaborate that description. In the first place it is one of 



