These seeds were planted in the usual manner, and the heights of the crossed and self-fertilised seedlings, when fully grown, are given in Tables 6/86 and 6/87.
The seven crossed plants in the first of these two tables average 95.25, and the seven self-fertilised 79.6 inches in height; or as 100 to 83. In half the pots a crossed plant, and in the other half a self-fertilised plant flowered first.
We now come to the seedlings raised from the other parent-plant B.
TABLE 6/87. Nicotiana tabacum (third generation). Seedlings from the self-fertilised plant B in pot 3, Table 6/85, of the last or second generation.
Heights of plants measured in inches.
Column 1: Number (Name) of Pot.
Column 2: From Self-fertilised Plant, crossed by a Crossed Plant.
Column 3: From Self-fertilised Plant again self-fertilised, forming the third Self-fertilised generation.
Pot 1 : 87 2/8 : 72 4/8. Pot 1 : 49 : 14 2/8.
Pot 2 : 98 4/8 : 73. Pot 2 : 0 : 110 4/8.
Pot 3 : 99 : 106 4/8. Pot 3 : 15 2/8 : 73 6/8.
Pot 4 : 97 6/8 : 48 6/8.
Pot 5 : 48 6/8 : 81 2/8. Pot 5 : 0 : 61 2/8.
Total : 495.50 : 641.75.
The seven crossed plants (for two of them died) here average 70.78 inches, and the nine self-fertilised plants 71.3 inches in height; or as 100 to barely 101. In four out of these five pots, a self-fertilised plant flowered before any one of the crossed plants. So that, differently from the last case, the self-fertilised plants are in some respects slightly superior to the crossed.
If we now consider the crossed and self-fertilised plants of the three generations, we find an extraordinary diversity in their relative heights. In the first generation, the crossed plants were inferior to the self-fertilised as 100 to 178; and the flowers on the original parent-plants which were crossed with pollen from a distinct plant yielded much fewer seeds than the self-fertilised flowers, in the proportion of 100 to 150. But it is a strange fact that the self-fertilised plants, which were subjected to very severe competition with the crossed, had on two occasions no advantage over them. The inferiority of the crossed plants of this first generation cannot be attributed to the immaturity of the seeds, for I carefully examined them; nor to the seeds being diseased or in any way injured in some one capsule, for the contents of the ten crossed capsules were mingled together and a few taken by chance for sowing. In the second generation the crossed and self-fertilised plants were nearly equal in height. In the third generation, crossed and self-fertilised seeds were obtained from two plants of the previous generation, and the seedlings raised from them differed remarkably in constitution; the crossed in the one case exceeded the self-fertilised in height in the ratio of 100 to 83, and in the other case were almost equal. This difference between the two lots, raised at the same time from two plants growing in the same pot, and treated in every respect alike, as well as the extraordinary superiority of the self-fertilised over the crossed plants in the first generation, considered together, make me believe that some individuals of the present species differ to a certain extent from others in their sexual affinities (to use the term employed by Gartner), like closely allied species of the same genus. Consequently if two plants which thus differ are crossed, the seedlings suffer and are beaten by those from the self-fertilised flowers, in which the sexual elements are of the same nature. It is known that with our domestic animals certain individuals are sexually incompatible, and will not produce offspring, although fertile with other individuals. (6/3. I have given evidence on this head in my 'Variation of Animals and Plants under Domestication' chapter 18 2nd edition volume 2 page 146.) But Kolreuter has recorded a case which bears more closely on our present one, as it shows that in the genus Nicotiana the varieties differ in their sexual affinities. (6/4.