320 APPENDIX 



observation completely or cannot be detected with certainty. This 

 circumstance is of great importance in the determination and 

 classification of the forms under which the offspring of the hybrids 

 appear. Henceforth in this paper those characters which are trans- 

 mitted entire, or almost unchanged in the hybridisation, and there- 

 fore in themseh^es constitute the characters of the hybrid, are 

 termed the dominant, and those which become latent in the process 

 recessive. The expression " recessive " has been chosen because the 

 characters thereby designated withdraw or entirely disappear in 

 the hybrids, but nevertheless reappear unchanged in their progeny, 

 as will be demonstrated later on. 



It was furthermore shown by the whole of the experiments that it 

 is perfectly immaterial whether the dominant character belongs to 

 the seed-bearer or to the pollen-parent; the form of the hybrid 

 remains identical in both cases. This interesting fact was also 

 emphasised by Gartner, w^th the remark that even the most 

 practised expert is not in a position to determine in a hybrid which 

 of the two parental species was the seed or the pollen plant. ^ 



Of the differentiating characters which were used in the experi- 

 ments the following are dominant: 



1. The round or roundish form of the seed with or without 

 shallow depressions. 



2. The yellow colouring of the seed albumen [cotyledons]. 



3. The grey, grey-bro^m, or leather-brown colour of the seed- 

 coat, in association with violet- red blossoms and reddish spots in 

 the leaf axils. 



4. The simply inflated form of the pod. 



5. The green colouring of the unripe pod in association with the 

 same colour in the stems, the leaf-veins and the calyx. 



6. The distribution of the flowers along the stem. 



7. The greater length of stem. 



With regard to this last character it must be stated that the 

 longer of the two parental stems is usually exceeded by the hybrid, 

 a fact which is possibly only attributable to the greater luxuriance 

 which appears in all parts of plants when stems of very different 

 length are crossed. Thus, for instance, in repeated experiments, 

 stems of 1 ft. and 6 ft. in length yielded without exception hybrids 

 which varied in length between 6 ft. and 7| ft. 



1 [Gartner, p. 223.] 



