Brassica Crosses. 3 



(3) To ascertain whether a Yellow-fleshed Turnip similar to those termed 



" Hybrid Turnips " by some seedsmen and farmers could be produced 

 by crossing the Swede (Brassica campestris, L., var. Napo-brassica, DC.) 

 with the White-fleshed Turnip (Brassica Rapa, L.). 



(4) Incidentally we wished to obtain light upon the relationship of the 



different cultivated forms of Brassica. 



Arising out of these experiments it became evident that the results had a 

 definite bearing on Mendelian phenomena. 



The plants used for crossing were grown in the open trial grounds, but flowers 

 selected for fertilisation were very carefully emasculated before the stamens 

 were ripe, and enclosed in small paper envelopes. The pollen was obtained only 

 from flowers which were allowed to open inside close-fitting paper bags to prevent 

 the possibility of stray pollen becoming mixed with that which was to be used 

 in the experiments. 



Many apparently unopened flowers were found to be useless for our purpose 

 on account of the attack of minute larvae of species of Meligethes and Cecidomyia, 

 which had fed on the immature pollen in the anther lobes and scattered some 

 of it in the inside of the flowers. 



In addition to the greatest care in emasculation and in the exclusion of insects 

 large and small, each stigma was examined with a Coddington lens to make 

 certain of its clean state before the application of the pollen. 



Over 80 distinct crosses were attempted. 



Taking into consideration the results obtained from them, they may be arranged 

 in three groups, viz : 



Group I. Crosses from which no seed was obtained. 



,, II. Those plants from which seeds were produced but the plants 

 raised from them proved self-sterile. 



,, III. Those plants from which seeds were obtained and the plants 

 from which were quite fertile among themselves. 



Group I. No seed resulted from the pollination of 



I Swedes, 



Cabbage } Turnips, 



Thousand-headed Kale r with -! Colza Rape, 

 Kohl Rabi Asparagus Kale, 



\ Ragged Jack Kale, 

 or the reverse pollinations. 



In some instances the pollen appeared to act as a stimulus to the growth of 

 the pericarp of the fruit, the pods growing to the normal size or even larger, but 

 the ovules were abortive. 



Group II. To this group belongs the cross 



<? ? <? ? 



White-fleshed White-fleshed 



m . on Swede, and its reciprocal Swede on m 



lurnip Turnip, 



which proved remarkable in many ways. 



