Table 6/93.  Primula veris.

Heights of plants measured in inches.

Column 1:  Number (Name) of Pot.

Column 2:  Height:  Legitimately crossed Plants.

Column 3:  Number of Flower-stems produced:  Legitimately crossed Plants.

Column 4:  Height:  Illegitimately crossed Plants.

Column 5:  Number of Flower-stems produced:  Illegitimately crossed
Plants.

Pot 1 :  9 :  16 :  2 1/8 :  3. 
Pot 1 :  8 :  :  3 4/8.

Pot 2 :  7 :  16 :  6 :  3. 
Pot 2 :  6 4/8 :  :  5 4/8.

Pot 3 :  6 :  16 :  3 :  4. 
Pot 3 :  6 2/8 :  :  0 4/8.

Pot 4 :  7 3/8 :  14 :  2 5/8 :  5. 
Pot 4 :  6 1/8 :  :  2 4/8.

Total :  56.26 :  62 :  25.75 :  15.

The average height of the eight tallest flower-stems on the crossed plants is here 7.03 inches, and that of the eight tallest flower-stems on the self-fertilised plants 3.21 inches; or as 100 to 46.  We see, also, that the crossed plants bore sixty-two flower-stems; that is, above four times as many as those (namely fifteen) borne by the self-fertilised plants.  The flowers were left exposed to the visits of insects, and as many plants of both forms grew close by, they must have been legitimately and naturally fertilised.  Under these circumstances the crossed plants produced 324 capsules, whilst the self-fertilised produced only 16; and these were all produced by a single plant in Pot 2, which was much finer than any other self-fertilised plant.  Judging by the number of capsules produced, the fertility of an equal number of crossed and self-fertilised plants was as 100 to 5.

In the succeeding year (1871) I did not count all the flower-stems on these plants, but only those which produced capsules containing good seeds.  The season was unfavourable, and the crossed plants produced only forty such flower-stems, bearing 168 good capsules, whilst the self-fertilised plants produced only two such flower-stems, bearing only 6 capsules, half of which were very poor ones.  So that the fertility of the two lots, judging by the number of capsules, was as 100 to 3.5.

In considering the great difference in height and the wonderful difference in fertility between the two sets of plants, we should bear in mind that this is the result of two distinct agencies.  The self-fertilised plants were the product of illegitimate fertilisation during five successive generations, in all of which, excepting the last, the plants had been fertilised with pollen taken from a distinct individual belonging to the same form, but which was more or less closely related.  The plants had also been subjected in each generation to closely similar conditions.  This treatment alone, as I know from other observations, would have greatly reduced the size and fertility of