[86]

Fig 206. Light Light

(Phalaris) [Figure]

Phalaris Right-Hand

Sept 16th

(1.3 scale 6 letterings Blue lines)

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79

Ipomoea

exceeded their opponents. A record was kept with respect to the plant which flowered first in each pot; and only two of the crossed flowered before one of the self-fertilised in the same pot; whilst eight of the self-fertilised flowered before the crossed first.

It thus appears that the crossed plants were slightly inferior in height & earliness of flowering to the self-fertilised. But the inferiority in height is so small, namely as 100 to 186, that I I should have felt very doubtful on this head, had I not cut down all the plants (except those in the crowed crowded pot, No. 10 X.) closed to the ground, and weighed them. The 27 crossed plants weighed 16 1/2 ounces, and the 27 self-fertilised plants 20 1/2 ounces; and this gives a ration of 100 to 124.

A self-fertilised plant, one of the same lot as those in Table 12, had been raised in a separate pot for a distinct purpose; and it proved partially sterile, the anthers containing very little pollen. Several flowers on this plant were crossed with the little pollen which could be obtained from the other flowers on the same

[Cross and self fertilisation, pp. 42-3: "Looking to each pair, it may be seen that only thirteen of the crossed plants, whilst eighteen of the self-fertilised plants exceed their opponents. A record was kept with respect to the plant which flowered first in each pot; and only two of the crossed flowered before one of the self-fertilised in the same pot; whilst eight of the self-fertilised flowered first. It thus appears that the crossed plants are slightly inferior in height and in earliness of flowering to the self-fertilised. But the inferiority in height is so small, namely as 100 to 106, that I should have felt very doubtful on this head, had I not cut down all the plants (except those in the crowded pot No. X.) close to the ground and weighed them. The twenty-seven crossed plants weighed 16 1/2 ounces, and the twenty-seven self-fertilised plants 20 1/2 ounces; and this gives a ratio of 100 to 124.

A self-fertilised plant of the same parentage as those in Table XII. had been raised in a separate pot for a distinct purpose; and it proved partially sterile, the anthers containing very little pollen. Several flowers on this plant were crossed with the little pollen which could be obtained from the other flowers on the same plant; and other flowers were self-fertilised."]

[87]

Sept 16th

Phalaris Left Hand on vertical glass Tracing B

[Figure] Light

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Ipomoea

plant; and other flowers were self-fertilised. From the seeds thus produced, four crossed and four self-fertilised plants were raised, which were planted in the usual manner on opposite sides of two pots. Each of All these four crossed plants were was inferior in height to their its opponents ; they averaged 78.18 inches, whilst the four self-fertilised plants averaged 84.8 inches; or as 100 to 108.* (Back) This case therefore confirms the last. Taking all the evidence together we must conclude that the strictly self-fertilised plants grew a little taller, were heavier, and generally flowered before them those derived from a cross between two flowers on the same plant. These latter plants thus present a wonderful contrast with those derived from a cross between two distinct individuals.

The effects on the offspring of a cross with a distinct a fresh stock belonging to of the same variety.─

From the previous two foregoing series of experiments we have seen, firstly, the good effects yielded during

[Cross and self fertilisation, pp. 44-5: "Several flowers on this plant were crossed with the little pollen which could be obtained from the other flowers on the same plant; and other flowers were self-fertilised. From the seeds thus produced four crossed and four self-fertilised plants were raised, which were planted in the usual manner on the opposite sides of two pots. All these four crossed plants were inferior in height to their opponents; they averaged 78.18 inches, whilst the four self-fertilised plants averaged 84.8 inches; or as 100 to 108.* This case, therefore, confirms the last. Taking all the evidence together, we must conclude that these strictly self-fertilised plants grew a little taller, were heavier, and generally flowered before those derived from a cross between two flowers on the same plant. These latter plants thus present a wonderful contrast with those derived from a cross between two distinct individuals.
* From one of these self-fertilised plants, spontaneously self-fertilised, I gathered twenty-four capsules, and they contained on an average only 3.2 seeds per capsule; so that this plant had apparently inherited some of the sterility of its parent.
The Effects on the Offspring of a Cross with a distinct or fresh Stock belonging to the same Variety.—From the two foregoing series of experiments we see, firstly, the good effects during several successive generations of a cross between distinct plants, although these were in some degree inter-related and had been grown under nearly the same conditions; and, secondly, the absence of all such good effects from a cross between flowers on the same plant; the comparison in both cases being made with the offspring of flowers fertilised with their own pollen."]