266 PLANT HYBRIDIZATION BEFORE MENDEL 



Macfarlane then cites four cases of Rhododendron crosses which 

 are color-intermediates between their parents, as follows : 



Rhododendron atrovirens purple-crimson 



ciliatum pink-white 



praecox (hybrid) intermediate 



arboreum scarlet 



caucasicum white 



nobleanum (hybrid) cerise 



" ciliatum pink-white 



" glaucum dull-pink 



" grievei (hybrid) pale whitish-pink 



chamaecistus pale pink 

 Menziesia empetriformis, var. drummondii rose-pink 



Bryanthus erectus (hybrid) intermediate 



This intermediacy of flower color in hybrids Macfarlane con- 

 sidered to be best exemplified by cases where yellow is involved, 

 due to the presence of yellow chromoplasts in the cells. The case 

 of hybrid Oxlips, crosses between Primrose and Cowslip, are 

 cited, as also cases of hybrid Hedychiums (fam. Zingiberaceae), 

 as follows : 



Hedychium gardnerianum orange 



X Hedychium coronarium white 



gave Hedychium, sadlerianum (hybrid) intermediate 



and 

 Hedychium sadlerianum 

 X Hedychium coronarium 

 gave Hedychium lindsayi pale, maize-white in bud, be- 



coming white in blossom 



In cases where yellow, red or blue occur in the same or neigh- 

 boring cells of a tissue, "the hybrid product may take after one 

 or the other of the parents in an apparently arbitrary way." As to 

 a possible theoretical explanation, Macfarlane says: 



"Suffice it to say that I regard many of the unequal blendings in hybrid 

 colour and structure to be due to incompatibility in chemical or mole- 

 cular union, and the resulting predominance of that colour which is the 

 more stable or readily evolved of the two." (6c.) 



A brief note is given upon inheritance of time of flowering. 



From the time of flowering of numerous species, and of hybrids, 



at the Edinburgh Botanic Garden, including a record since 1889, 



of 800 plants in the rock garden, including also several hybrids 



and their parents, it is concluded that: 



"These, supplemented by limited observations of my own, all point 

 distinctly to a flowering period in hybrids closely intermediate between 

 the parents." (6c.) 



