HYBRIDISM 37 



added, the forms of the same undoubted species when 

 illegitimately united behave in exactly the same manner 

 as do two distinct species when crossed. This led me 

 carefully to observe during fo-ur years many seedlings, 

 raised from several illegitimate unions. The chief result 

 is that these illegitimate plants, as they may be called, 

 are not fully fertile. It is possible to raise from dimor- 

 phic species both long-styled and short-styled illegitimate 

 plants, and from trimorphic plants all three illegitimate 

 forms. These can then be properly united in a legitimate 

 manner. When this is done, there is no apparent reason 

 why they should not yield as many seeds as did their 

 parents when legitimately fertilized. But such is not the 

 case. They are all infertile, in various degrees; some 

 being so utterly and incurably sterile that they did not 

 yield during four seasons a single seed or even seed- 

 capsule. The sterility of these illegitimate plants, when 

 united with each other in a legitimate manner, may be 

 strictly compared with that of hybrids when crossed 

 inter se. If, on the other hand, a hybrid is crossed with 

 either pure parent-species, the sterility is usually much 

 lessened: and so it is when an illegitimate plant is 

 fertilized by a legitimate plant. In the same manner 

 as the sterility of hybrids does not always run parallel 

 with the difficulty of making the first cross between the 

 two parent-species, so the sterility of certain illegitimate 

 plants was unusually great, while the sterility of the 

 union from which they were derived was by no means 

 great. With hybrids raised from the same seed-capsule 



.tvle^ithe degree of sterility is innately variable, so it is in a 

 marked manner with illegitimate plants. Lastly, many 



l\ bjihybrids are profuse and persistent flowerers, while other 



