45° 



BOTANICAL GAZETTE 



[DECEMBER 



that it gives no reversions to f. typica. All of the aberrant plants 

 in the cultures, both from self-pollination and from pollination with 

 f. typica, are mutations belonging to the characteristic group. 

 As in the case of mut. formosa, most of the secondary mutations 

 were mut. setacea. 



The small culture of f. typicaXmut. albicans emphasizes the fact 

 that the composition of the culture is conditioned by the female 



gamete. As in the case of the 

 analogous cross f. typicaXmut. 

 formosa, the progeny is just 

 what we should expect from 

 self-pollination of the typica 

 parent. 



Mut. revoluta. — Only one 

 small progeny was obtained 

 from this nearly sterile muta- 

 tion. It showed that the form 

 reproduces itself except for 

 throwing other mutations of 

 the characteristic group. None 

 of the crosses made with mut. 

 revoluta were successful, but 

 there can be little doubt, from 

 collateral evidence, that mut. 

 revoluta, as well as mut. albi- 

 cans, follows the same type of 

 inheritance as mut. formosa. 

 Mut. setacea. — So far as 

 can be determined, this form 

 comes entirely true from seed, 

 and represents the most 

 extreme modification which can take place in the direction 

 followed by the group of characteristic mutations. Although 

 the crosses with f. typica have so far not been successful, 

 it is probable that this extreme reduction phase would also 

 be dominant when introduced into the cross as the female 

 gamete. 



Fig. 12, — Mut. formosa: 2 rosettes, 

 Lexington E-5-206 and 207, from the Fj 

 progeny of £. typica; both are shown in 

 fig. 5. 



