228 



MASS MUTATIONS AND TWIN HYBRIDS OF 



lata type. The cultures showed the same splitting and the same 

 types as in the first generation after the cross. I counted the lata 

 in May and found 13, 15, and 19 per cent, and the ovata in May and 

 August; they amounted to 35—51 per cent among 234 individuals. 

 The remainder were partly lutea and brunnea and partly mutants 

 of different types. Self-fertilized specimens of lata from crosses with 

 0. Hookeri, 0. Cockerelli, and 0. biennis Chicago have given analo- 

 gous splittings, and the experiments just described simply confirm 

 the conclusions drawn from them (5, pp. 252, 254, 255). 



E. Second generation of crosses with 0. Lamarckiana. 



As is well known, the twin hybrids from crosses of 0. Lamarcki- 

 ana are constant in their progeny, with the exception of the laeta 

 from the crosses with 0. Hookeri, which splits into laeta and velutina 

 in the succeeding generations. For this reason I wanted to know 

 whether the triple hybrids just described would be constant after 

 self-fertilization or split. 1 found that none of them split off one of 

 the two others, and in so far they were constant. On the other hand, 

 some secondary marks, which were not observed in the first gene- 

 ration, turned up in the second, and thus the constancy was not 

 absolute. Since these splittings had no significance for the main 

 object of my study, I have not followed them up. 



Table VII 



Cultures of second generation 



Cross 



Cross 



O. grandiflorax Lamarcki- 

 ana 



O. grandiflora Ioreax La- 

 marckiana 



O. Lamarckiana x grandi- 

 flora | 



O. Lamarckiana x grandi- 

 flora lorea 



O. grandiflora x nanella .. 



O. grandiflorax nanella .. 



O. grandiflora Ioreax nan- 

 ella 



O. nanella x grandiflora .. 



O. lata x grandiflora 



O. grandiflora ochraceax 

 Lamarckiana 



O. grandiflora ochraceax 

 nanella 



1914 



1914 



1913 



1914 

 1913 

 1913 



1914 

 1913 

 1914 



1914 



1914 



Second 

 gene- 

 ration 



1916 



1916 



1916 



1916 

 1915 

 1916 



1916 

 1915 

 1916 



1916 



1916 



ovata 



+ 

 + 



-;- 



lutea 



- 1 - 



+ 



brunnea contraria 



+ 



+ 



+ 



+ 

 + 



+ 



+ 

 + 



