BRASSICA CROSSES. 



43 



BRASSICA CROSSES. 



[Abstract of Paper read before the Scientific Committee, March 3, 1908.] 



Mr. A. W. Sutton, F.L.S., V.M.H., gave an account of his experiments 

 in crossing species and varieties of the genus Brassica, illustrating his 

 remarks by means of lantern slides. The experiments were started in 

 1900 with the primary object of ascertaining which forms commonly 

 cultivated could be intercrossed. At first several varieties of Brassica 

 oleracea were planted close together in order that intercrossing might 

 take place freely, and as a result of sowing seed a very heterogeneous lot 

 of nondescript forms, few of which were true to the parental type, were 

 obtained. A repetition of the experiment on slightly different lines gave 

 similar results, but in this second set of experiments varieties of turnip, 

 swede, and oil-yielding rape were included. None of the forms derived 

 from seed of any of the varieties of B. oleracea showed any influence of 

 rape, swede, or turnip, and vice versa, but the varieties of B. oleracea were 

 found to cross freely between themselves as before, and the same was 

 true of many varieties of turnips, swede, and rape. Later the experiments 

 were still further extended, so that it was definitely known what pollen 

 was used in producing the seed of the various varieties tried. Among the 

 results yielded were the following : — 



(a) No seed was produced when cabbage, kohlrabi, and thousand - 

 headed kale were crossed with swede, turnip, colza rape, asparagus kale, 

 or ragged Jack kale. 



(b) Swede $ x turnip $ yielded plump seed of a black colour and 

 excellent germinative capacity, but the reciprocal cross yielded pale 

 shrivelled seed which germinated with difficulty and produced weakly 

 plants, which, however, under careful treatment developed as strongly as 

 the others and showed similar characters. The flowers proved sterile, 

 and the plants were in the main intermediate between their parents — facts 

 which Mr. Sutton thought pointed to the specific distinctness of the 

 swede and the turnip. The plants were so different in character from the 

 so-called " hybrid " yellow-fleshed turnip that it would appear very unlikely 

 that the latter has originated by the crossing of the swede and the turnip. 

 Hybrids which proved sterile or were not hardy were also reciprocally 

 raised between rape and swede, rape and turnip, asparagus kale and 

 yellow tankard swede, ragged Jack kale and yellow swede, asparagus kale 

 and white turnip. 



(c) Other crosses gave abundant and fertile seeds, the plants from 

 which produced seed in the second generation, when in every case 

 segregation occurred. This was the case when ragged Jack kale was 

 reciprocally crossed with white swede, kohlrabi with thousand-headed 

 kale, kohlrabi with drumhead cabbage, thousand-headed kale j with 

 drumhead cabbage $ and swede $ with asparagus kale ? (there were no 

 reciprocal crosses in the last two cases). In many cases the segregation 



