32 RECIPROCAL DIMORPHISM [Chap. IX. 



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 pro- 

 duce few flowers, and are weak, miserable dwarfs; 

 exactly similar cases occur with the illegitimate off- 

 spring 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 re- 

 spects 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 seeds, 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 

 the common view, that his two varieties were as good 

 and as distinct species as any in the world; but he would 

 be completely mistaken. 



