224 BREEDING 



The theory put forward to explain the results of 

 crossing a pink-flowered with a white-flowered pea 

 will now be briefly set forth on the same lines. This 

 case is given as well, because, for practical purposes, 

 it is more convenient than the seed- coats ; in the 

 first place, the characters, pertaining as they do to 

 the flowers, form more suitable objects for demonstra- 

 tion in the garden than the seed- coat characters ; 

 though these are very useful as permanent exhibits. 

 In the second place, for the purposes of experimenta- 

 tion, characters of the flower are much more conveni- 

 ent than those of the seed-coat, because in the case of 

 the former the character of the individuals being 

 mated can be seen at the time the cross is being 

 made — indeed, it cannot but be seen; whilst in 

 the case of the seed-coat characters the actual 

 characters of the plants mated cannot be determined 

 until they are dry and ripe, except indirectly and 

 imperfectly by the known fact that a white flower 

 is associated with a white seed- coat, and a purple 

 one with a grey or purple- spotted grey seed-coat. 



The instances of flower colour and of seed-coat 

 colour also follow one another in a natural sequence, 

 inasmuch as the interpretation of the former is made 

 more readily intelligible by a familiarity with the 

 theory which is put forward to explain the latter. 

 For in the case of the flower colour it is unlikely that 

 the theory that the purple was due to the simultaneous 

 presence of two colour factors (namely, blue and pink) 

 belonging to distinct pairs, would have suggested 

 itself if the similarity of the composition of the 



