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Effects of Cross and Self Fertilisation in the Vegetable Kingdom eBook

This eBook from the Gutenberg Project consists of approximately 459 pages of information about Effects of Cross and Self Fertilisation in the Vegetable Kingdom.

The plants were turned out of the two pots without being disturbed and planted in the open ground, in order that they might grow more vigorously.  In the following summer all the self-fertilised and some of the quasi-crossed plants were covered by a net.  Many flowers on the latter were crossed by me with pollen from a distinct plant, and others were left to be crossed by the bees.  These quasi-crossed plants produced rather more seed than did the original ones in the great clump when left to the action of the bees.  Many flowers on the self-fertilised plants were artificially self-fertilised, and others were allowed to fertilise themselves spontaneously under the net, but they yielded altogether very few seeds.  These two lots of seeds—­the product of a cross between distinct seedlings, instead of as in the last case between plants multiplied by stolons, and the product of self-fertilised flowers—­were allowed to germinate on bare sand, and several equal pairs were planted on opposite sides of two large pots.  At a very early age the crossed plants showed some superiority over the self-fertilised, which was ever afterwards retained.  When the plants were fully grown, the two tallest crossed and the two tallest self-fertilised plants in each pot were measured, as shown in Table 3/28.  I regret that from want of time I did not measure all the pairs; but the tallest on each side seemed fairly to represent the average difference between the two lots.

Table 3/28.  Origanum vulgare.

Heights of Plants measured in inches.

Column 1:  Number (Name) of Pot.

Column 2:  Crossed Plants (two tallest in each pot).

Column 3:  Self-fertilised Plants (two tallest in each pot).

Pot 1 :  26 :  24. 
Pot 1 :  21 :  21.

Pot 2 :  17 :  12. 
Pot 2 :  16 :  11 4/8.

Total :  80.0 :  68.5.

The average height of the crossed plants is here 20 inches, and that of the self-fertilised 17.12; or as 100 to 86.  But this excess of height by no means gives a fair idea of the vast superiority in vigour of the crossed over the self-fertilised plants.  The crossed flowered first and produced thirty flower-stems, whilst the self-fertilised produced only fifteen, or half the number.  The pots were then bedded out, and the roots probably came out of the holes at the bottom and thus aided their growth.  Early in the following summer the superiority of the crossed plants, owing to their increase by stolons, over the self-fertilised plants was truly wonderful.  In Pot 1, and it should be remembered that very large pots had been used, the oval clump of crossed plants was 10 by 4 1/2 inches across, with the tallest stem, as yet young, 5 1/2 inches in height; whilst the clump of self-fertilised plants, on the opposite side of the same pot, was only 3 1/2 by 2 1/2 inches across, with the tallest young stem 4 inches in height.  In Pot 2, the clump of crossed plants was 18 by 9

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