Breeding experiments which show that hybridisation and mutation etc. 257 



In all the F., hybrids in 1912, the time of forming stems was inter- 

 mediate between that of the original parents. Thus my grandiflora 

 culture of that year (221 plants) had already formed tall, slender stems 

 by May 25''', while of the rubricalyx culture (200 plants) only one 

 in eight had begun to form stems by June 22. 



In the F2 hybrids (17 families, table III), nearly all had formed 

 stems about 18 inches high by June 14'''. In 7 families in which the 



Fig. 20. Rubricalyx X grandiflora, F.,. FoUage p. s. 



F, of grandiflora x rubricalyx or the reciprocal was crossed back with 

 grandiflora, the time of stem-formation was not observed to be markedly 

 different from that of the F.2 cultures. 



The time of blooming of rubricalyx was unfortunately not recorded. 

 The grandiflora plants, notwithstanding their luxiniant growth, failed 

 to produce flowers or buds, with the exception of two plants which 

 began to bloom about the end of September. The F.> families from 



Induktive Abstammunga- und Vererbungslehre. XI. 17 



