MR. A. W. SUTTON ON BRASSICA CROSSES, 339 
The chief objects we had in view were :— 
(1) To determine which varieties of Brassica would cross with each 
other, and whether the plants of the first filial generation (F 1) 
were fertile or sterile. 
(2) To draw such conclusions as might be possible from results thus 
obtained concerning the origin of the principal distinet types of 
Swedes and Turnips, and more especially to ascertain whether the 
White-fleshed and Yellow-fleshed Swedes had a common origin, 
as also the White-fleshed and Yellow-fleshed Turnips. 
(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 fertilization 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 larve of species of Meligethes and 
Cecidomyia, which had fed on the immature pollen т the anther lobes 
and scattered some of it in the inside of the flowers. 
In addition to the greatest care in emaseulation 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 distinet 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. 
2B 2 
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