4 Brassica Crosses. 



When the Swede is fertilized by the Turnip, that is, when the Swede is made the 

 seed-bearer, the seeds obtained are abundant. They are large and black-coated 

 like those of the typical Swede, and contain embryos which grow vigorously into 

 fine healthy plants. 



In the reciprocal cross, that is. where the Turnip is fertilized by Swede pollen, 

 the Turnip being the seed-bearer, the seeds produced are rather paler in coat colour 

 than those of the normal Turnip and always smaller and shrivelled. Moreover, 

 it is difficult to germinate and rear seedlings from them in open ground, though 

 there is little difficulty in doing this with the seeds of the reverse cross. 



These points have been tested many times during two seasons, always with the 

 same results. 



At first the seeds of the crosses were sown in carefully prepared beds in the 

 open ground ; and from the fact that no plants were obtained from the seeds of 

 the Swede < on Turnip $ cross, we were inclined to conclude that the embryos in 

 the seeds were abortive and incapable of growth. 



However, in 1906 seeds from reciprocal crossings were again obtained, which 

 showed the same striking differences in size, colour, and shape as were previously 

 seen in the seeds, but instead of sowing them at once in the open ground they \v-iv 

 germinated on blotting-paper and the seedlings planted out. Those of the Swede <$ 

 on Turnip $ were weak, but after careful management ultimately grew into plants 

 as large as those from the Turnip $ on Swede $ cross. Moreover, the characters of 

 the full-grown plants proved to be the same whichever way the cross was made. 



The general facies of the plants was intermediate between the two parents. 

 The leaves were glaucous like Swede leaves, but more hispid and more like those 

 of the Turnip in shape. The " bulb " resembled the Swede in form and nock 

 perhaps more than the Turnip, but the flesh was white like the latter. The flowers 

 were almost as large as those of the Swede, but canary-yellow in colour, like those 

 of the White-fleshed Turnip or White-fleshed Swede. They were abundant and 

 apparently normal, but produced no seed although many were pollinated by 

 hand. It was discovered later that the pollen was abnormal in form and structure, 

 many of the pollen mother-cells having undergone peculiar changes which we hope 

 to investigate further in the coming season. 



The very marked sterility and the intermediate character of the plants obtained 

 when the Swede (Brassica campestris, L., var. Napo-brassica Rutabaga, DC.) and 

 White-fleshed Turnip (Brassica Rapa, L.) are crossed, seem to point strongly to 

 the conclusion that they are true hybrids and that the parents are specifically 

 distinct. 



Apart from the fact that the plants are sterile, they are so different in character 

 from the so-called " hybrid " yellow-fleshed Turnip, that it does not appear likely 

 that the latter has originated by crossing the Swede and Turnip. 



In addition to the Turnip x Swede cross just described, many others were made, 

 including the following, which should probably be placed in this group : 



Colza Rape on Yellow-fleshed Tankard Swede. 



Colza Rape on White-fleshed Round Swede. 



Colza Rape on Yellow-fleshed Turnip. 



White-fleshed Turnip on Colza Rape. 



