But my anticipation was quite wrong, for they profited in a less degree. An analogous result followed in the case of Eschscholtzia, in which the offspring of the plants of Brazilian parentage (which were partially self-sterile) did not profit more from a cross, than did the plants of the far more self-fertile English stock. The above two lots of crossed and self-fertilised seeds from the same plant of Reseda odorata, after germinating on sand, were planted on opposite sides of five pots, and measured as in the last case, with the result in Table 4/39.

TABLE 4/39. Reseda odorata (seedlings from a semi-self-sterile plant).

Heights of plants to the summits of the leafy stems, flower-stems not included, measured in inches.

Column 1: Number (Name) of Pot.

Column 2: Crossed Plants.

Column 3: Self-fertilised Plants.

Pot 1 : 33 4/8 : 31. Pot 1 : 30 6/8 : 28. Pot 1 : 29 6/8 : 13 2/8. Pot 1 : 20 : 32.

Pot 2 : 22 : 21 6/8. Pot 2 : 33 4/8 : 26 6/8. Pot 2 : 31 2/8 : 25 2/8. Pot 2 : 32 4/8 : 30 4/8.

Pot 3 : 30 1/8 : 17 2/8. Pot 3 : 32 1/8 : 29 6/8. Pot 3 : 31 4/8 : 24 6/8. Pot 3 : 32 2/8 : 34 2/8.

Pot 4 : 19 1/8 : 20 6/8. Pot 4 : 30 1/8 : 32 6/8. Pot 4 : 24 3/8 : 31 4/8. Pot 4 : 30 6/8 : 36 6/8.

Pot 5 : 34 6/8 : 24 5/8. Pot 5 : 37 1/8 : 34. Pot 5 : 31 2/8 : 22 2/8. Pot 5 : 33 : 37 1/8.

Total : 599.75 : 554.25.

The average height of the twenty crossed plants is here 29.98, and that of the twenty self-fertilised 27.71 inches; or as 100 to 92. These plants were then cut down and weighed; and the crossed in this case exceeded the self-fertilised in weight by a mere trifle, namely, in the ratio of 100 to 99. The two lots, left freely exposed to insects, seemed to be equally fertile.

The remainder of the seed was sown in two adjoining rows in the open ground; and the eight tallest plants in each row were measured, with the result in Table 4/40.

TABLE 4/40. Reseda odorata, (seedlings from a semi-self-sterile plant, planted in the open ground).

Heights of plants measured in inches.

Column 1: Crossed Plants.

Column 2: Self-fertilised Plants.

28 2/8 : 22 3/8. 22 4/8 : 24 3/8. 25 7/8 : 23 4/8. 25 3/8 : 21 4/8. 29 4/8 : 22 5/8. 27 1/8 : 27 3/8. 22 4/8 : 27 3/8. 26 2/8 : 19 2/8.

Total : 207.38 : 188.38.

The average height of the eight crossed plants is here 25.92, and that of the eight self-fertilised plants 23.54 inches; or as 100 to 90.

9. VIOLACEAE.--Viola tricolor.

Whilst the flowers of the common cultivated heartsease are young, the anthers shed their pollen into a little semi-cylindrical passage, formed by the basal portion of the lower petal, and surrounded by papillae. The pollen thus collected lies close beneath the stigma, but can seldom gain access into its cavity, except by the aid of insects, which pass their proboscides down this passage into the nectary. (4/5. The flowers of this plant have been fully described by Sprengel, Hildebrand, Delpino, and H. Muller. The latter author sums up all the previous observations in his 'Befruchtung der Blumen' and in 'Nature' November 20, 1873 page 44. See also Mr. A.W. Bennett in 'Nature' May 15, 1873 page 50 and some remarks by Mr. Kitchener ibid page 143. The facts which follow on the effects of covering up a plant of V. tricolor have been quoted by Sir J. Lubbock in his 'British Wild Flowers' etc. page 62.) Consequently when I covered up a large plant of a cultivated variety, it set only eighteen capsules, and most of these contained very few good seeds--several from only one to three; whereas an equally fine uncovered plant of the same variety, growing close by, produced 105 fine capsules. The few flowers which produce capsules when insects are excluded, are perhaps fertilised by the curling inwards of the petals as their wither, for by this means pollen-grains adhering to the papillae might be inserted into the cavity of the stigma.

Charles Darwin

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