342 APPENDIX 



these, constant without exception. Also of those plants which 

 possessed violet flowers and brown or black seed, some did not vary 

 again in these respects in the next generation; the majority, how- 

 ever, yielded, together with offspring exactly like themselves, some 

 which displayed white flowers and white seed-coats. The red 

 flowering plants remained so slightly fertile that nothing can be 

 said with certainty as regards their further development. 



Despite the many disturbing factors with which the observations 

 had to contend, it is nevertheless seen by this experiment that the 

 development of the hybrids, with regard to those characters which 

 concern the form of the plants, follows the same laws as in Pisum. 

 With regard to the colour characters, it certainly appears difficult 

 to perceive a substantial agreement. Apart from the fact that from 

 the union of a white and a purple-red colouring a whole series of 

 colours results [in F 2 ], from purple to pale violet and white, the 

 circumstance is a striking one that among thirty-one flowering 

 plants only one received the recessive character of the white colour, 

 while in Pisum this occurs on the average in every fourth plant. 



Even these enigmatical results, however, might probably be 

 explained by the law governing Pisum if we might assume that the 

 colour of the flowers and seeds of Ph. multiflorus is a combination of 

 two or more entirely independent colours, which individually act 

 like any other constant character in the plant. If the flower- 

 colour A were a combination of the individual characters A\ 

 + A 2 + • • • which produce the total impression of a purple colora- 

 tion, then by fertilisation with the differentiating character, 

 white colour, a, there would be produced the hybrid unions A\a + 

 A 2 a + . . . and so would it be with the corresponding colouring of 

 the seed-coats. 1 According to the above assumption, each of these 

 hybrid colour unions would be independent, and would conse- 

 quently develop quite independently from the others. It is then 

 easily seen that from the combination of the separate develop- 

 mental series a complete colour-series must result. If, for instance, 

 A = Ai+ A 2 , then the hybrids A x a and A 2 a form the develop- 

 mental series — 



Ax + ZAxa + a, A 2 + 2A 2 a + a. 



1 [As it fails to take account of factors introduced by the albino this represen- 

 tation is imperfect. It is however interesting to know that Mendel realized the fact 

 of the existence of compound characters, and that the rarity of the white recessives 

 was a consequence of this resolution.] 



