376 OENOTHERA RUBRINERVIS, A HALF MUTANT. 



8. The constitution of the gametes of 0. rubrinervis can directly 

 be proven by a cross with 0. deserens, since 0. rubrinervis=(deserens 

 -\-velutina)xO. deserens produces 0. deserens and (0. deserensx 

 velutina) or rubrinervis. 



9. Crosses ot 0. rubrinervis with 0. Lamarckiana give three types 

 of hybrids, besides about one-fou r th empty seeds. One type exactly 

 resembles 0. Lamarckiana and is constant in its progeny. A second 

 type called lucida has broader and more shiny leaves, and after self- 

 fertilization splits off brittle specimens. The third type is either 

 subrobusta or rubrinervis, and in the first case may produce the 

 brittle form in the second generation. All these phenomena are easily 

 explained by the proposed formula for the constituion of 0. rubrinervis 

 as a half mutant. They were confirmed by means of crosses with 

 0. nanella and some other mutants. 



10. 0. oblonga is quite analogous to 0. rubrinervis, since it must 

 arise through a mutation of the typical sexual cells of 0. Lamarckiana, 

 leaving the velutina gametes unchanged. Contrary to 0. rubrinervis, 

 however, the two lethal factors remain in their condition, and 

 moreover the mutated gametes must be assumed to become sup- 

 pressed in the pollen of the mutant. 



11. 0. nanella seems to arise through mutations in the velutina 

 gametes of 0. Lamarckiana, since after crosses with other species or 

 mutants it is not split off by the laeta hybrids, but only by those of 

 the type velutina. 



(The Botanical Gazette Vol. LXVII, 1919., p. 1). 



