The effects of A cross with A fresh stock.

Some flowers on a crossed plant of the last or second generation were fertilised, without being castrated, by pollen taken from a plant of the same variety, but not related to my plants, and brought from a nursery garden (whence my seeds originally came) having a different soil and aspect.  The flowers on the self-fertilised plants of the last or second generation (Table 4/29) were allowed to fertilise themselves spontaneously under a net, and yielded plenty of seeds.  These latter and the crossed seeds, after germinating on sand, were planted in pairs on the opposite sides of six large pots, which were kept at first in a cool greenhouse.  Early in January their heights were measured to the tips of their leaves.  The thirteen crossed plants averaged 13.16 inches in height, and the twelve (for one had died) self-fertilised plants averaged 13.7 inches, or as 100 to 104; so that the self-fertilised plants exceeded by a little the crossed plants.

Table 3/30.  Brassica oleracea.

Weights in ounces of plants after they had formed heads.

Column 1:  Number (Name) of Pot.

Column 2:  Crossed Plants from Pollen of fresh Stock.

Column 3:  Self-fertilised Plants of the Third Generation.

Pot 1 :  130 :  18 2/4.

Pot 2 :  74 :  34 3/4.

Pot 3 :  121 :  17 2/4.

Pot 4 :  127 2/4 :  14.

Pot 5 :  90 :  11 2/4.

Pot 6 :  106 2/4 :  46.

Total :  649.00 :  142.25.

Early in the spring the plants were gradually hardened, and turned out of their pots into the open ground without being disturbed.  By the end of August the greater number had formed fine heads, but several grew extremely crooked, from having been drawn up to the light whilst in the greenhouse.  As it was scarcely possible to measure their heights, the finest plant on each side of each pot was cut down close to the ground and weighed.  In Table 4/30 we have the result.

The six finest crossed plants average 108.16 ounces, whilst the six finest self-fertilised plants average only 23.7 ounces, or as 100 to 22.  This difference shows in the clearest manner the enormous benefit which these plants derived from a cross with another plant belonging to the same sub-variety, but to a fresh stock, and grown during at least the three previous generations under somewhat different conditions.

The offspring from A cut-leaved, curled, and variegated white-green
cabbage crossed with A cut-leaved, curled, and variegated crimson-green
cabbage, compared with the self-fertilised offspring from the two
varieties.