striped Flowers 313 



parts. But its variability is restricted to tliis 

 group. And large as the group may seem on 

 first inspection, it is in reality very narrow. 

 Many monstrosities, such as fasciated branch- 

 es, pitchers, split leaves, peloric flowers, and 

 others constitute such ever-sporting varieties, 

 repeating their anomalies year by year and gen- 

 eration after generation, changing as much as 

 possible within limits, but remaining absolutely 

 true to these limits as long as the variety exists. 



It must be a very curious combination of the 

 unit-characters which causes such a state of 

 continuous variability. The pure quality of the 

 species must be combined with the peculiarity 

 of the variety in such a way, that the one ex- 

 cludes the other, or modifies it to some extent, 

 although both never fully display themselves 

 in the same part of the same plant. A corolla 

 cannot be at once monochromatic and striped, 

 nor can the same part of stem be twisted and 

 straight. But neighboring organs may show 

 the opposite attributes side by side. 



In order to look closer into the real mechan- 

 ism of this form of variability, and of this con- 

 stant tendency to occasional reversions, it will 

 be best to limit ourselves first to a single case, 

 and to try to gather all the evidence, which 

 can be obtained by an examination of the he- 

 reditary relations of its sundry constituents. 



