Breeding experiments which show that hybridisation and mutation etc. 225 



and, remaining rosettes, failed to yield the full data which they would 

 otherwise have furnish.ed. 



Most ot the offspring derived from the self-pollination of the 

 original rubricalyx mutant were accidentally destroyed, only 12 plants 

 surviving, of which 11 were rubricalyx and i rubrinervis. Open- 

 pollinated seeds of the mutant, which as it grew was surrounded on 

 all sides by rubrinervis plants, yielded in 1909, 112 plants, of which 

 67 were rubricalyx and 45 rubrinervis. This result is intermediate 



Fig. 7. Young plant of Birkenhead race of O. grandiflora, 

 showing omission of the rosette stage. 



between a 3 : i ratio, such as would be expected if pure self-pollination 

 had taken place, and a i : i which would be anticipated if pollination 

 was wholly from rubrinervis. As will be seen from pedigree i, one of 

 these rubricalyx plants when tested proved itself homozygous (RR) in 

 the next generation, and one of the recessive (rubrinervis) plants was 

 also shown to be homozygous (rr ). The recessives, whenever tested, 

 invariably yield only the recessive character (see Gates, 1911b, p. 365). 

 In the second self-pollinated generation from the rubricalyx mutant 

 the plant (No. 070. 23) with which most of the experiments were con- 



Induktive Abstämmlings- und Vererbungslehre. XI. I 5 



