344 



PERMANENT HYBRIDS 



directly. In the former case the permanent heterozygote will 

 appear only following hybridisation and after an interval during 

 which changes have taken place that are necessary to make the 

 segregation of homozygotes from the hybrid impossible or difficult. 

 The steps in this indirect process of origin are shown in Campanula 

 (Gairdner and D., 1931 and unpub.) where crosses between 

 structurally different forms give rings of six, eight and ten, which 

 yield a high proportion of their like when selfed. Probably both 

 the direct and the indirect method have played some part in the 

 origin of the complex heterozygote species of CEnothera, 



Table 54 

 Summary of Ring-forming Properties in Forms of CEnothera * 



I. Species. 



Species 



Heterozygotes : — 

 CE. grandiflora . 

 Cockerelli 

 strigosa 

 muricata 

 suaveolens 

 Lamarckiana 

 biennis 



Homozygotes : 

 CE. jranciscana . 

 Hookeri 

 piirpurata 



Complex constitution 



acuens . truncans 

 curtans . elongans 

 deprimens . stringens 

 curvans.rigens 

 Havens . albicans 

 velans.gaudens 

 rubens. albicans 



''franciscana . ''franciscana 

 ''Hookeri . ''Hookeri 

 ''purpurata . ''purpurata 



2. Hybrids between Heterozygotes. 

 Heterozygotes : 



(E. Lamarckiana X 



strigosa. 

 (and reciprocally) 



CE. Lamarckiana x 



suaveolens. 

 (and reciprocally) 



CE. suaveolens X 

 strigosa. 



(i) velans. stringens . 

 (ii) gaudens. stringens 

 (iii) deprimens. velans 

 (iv) deprimens. gaudens 

 (i) velans. flavens 

 (ii) gaudens. flavens . 

 (iii) albicans. velans . 

 (iv) albicans. gaudens 

 (i) flavens . stringens 

 (ii) albicans . stringens 

 (iii) deprimens . flavens 

 (iv) albicans. deprimens 



Configuration 



(14) 



(14) 



(14) 



(M) 

 (12) + (2) 

 (12) + (2) 

 (8) H- (6) 



7(2) 



7(2) 



7(2) 



(6) + (4) + 2 (2) 



(14) 



(10) + 2 (2) 



(10) + 2 (2) 



2 (4) + 3 (2) 



(12) + (2) 



(14) 



(8) + (6) 



(4) + 5 (2) 



(12) + (2) 



(12) + (2) 



(not obtained) 



* From D., 1931 d ; Catcheside, 1933 ; Cleland, i935- 



