32 RECIPROCAL DIMORPHISM [Chap. IX. 



the union from which they were derived was by no 

 means great. With hybrids raised from the same seed- 

 capsule the degree of sterility is innately variable, so it 

 is in a marked manner with illegitimate plants. Lastly, 

 many hybrids are profuse and persistent flowerers, 

 whilst other and more sterile hybrids produce few 

 flowers, and are weak, miserable dwarfs ; exactly 

 similar cases occur with the illegitimate offspring of 

 various dimorphic and trimorphic plants. 



Altogether there is the closest identity in character and 

 behaviour between illegitimate plants and hybrids. It is 

 hardly an exaggeration to maintain that illegitimate 

 plants are hybrids, produced within the limits of the same 

 species by the improper union of certain forms, whilst 

 ordinary hybrids are produced from an improper union 

 between so-called distinct species. We have also already 

 seen that there is the closest similarity in all respects 

 between first illegitimate unions and first crosses between 

 distinct species. This will perhaps be made more fully 

 apparent by an illustration ; we may suppose that a 

 botanist found two well-marked varieties (and such 

 occur) of the long-styled form of the trimorphic Lythrum 

 salicaria, and that he determined to try by crossing 

 whether they were specifically distinct. He would find 

 that they yielded only about one-fifth of the proper 

 number of seed, and that they behaved in all the other 

 above specified respects as if they had been two distinct 

 species. But to make the case sure, he would raise 

 plants from his supposed hybridised seed, and he would 

 find that the seedlings were miserably dwarfed and 

 utterly sterile, and that they behaved in all other 

 respects like ordinary hybrids. He might then main- 

 tain that he had actually proved, in accordance with 



