and fertility (when these two latter points were attended to), the present case must be looked at as an anomaly not affecting the general rule.  The most probable explanation is that the seeds from which the crossed plants of the third generation were raised were not well ripened; for I have observed an analogous case with Iberis.  Self-fertilised seedlings of this latter plant, which were known to have been produced from seeds not well matured, grew from the first much more quickly than the crossed plants, which were raised from better matured seeds; so that having thus once got a great start they were enabled ever afterwards to retain their advantage.  Some of these same seeds of the Iberis were sown on the opposite sides of pots filled with burnt earth and pure sand, not containing any organic matter; and now the young crossed seedlings grew during their short life to double the height of the self-fertilised, in the same manner as occurred with the above two sets of seedlings of Petunia which were much crowded and thus exposed to very unfavourable conditions.  We have seen also in the eighth generation of Ipomoea that the self-fertilised seedlings raised from unhealthy parents grew at first very much more quickly than the crossed seedlings, so that they were for a long time much taller, though ultimately beaten by them.

4, 5, 6.  Eschscholtzia californica.

Four sets of measurements are given in Table 7/A.  In one of these the crossed plants exceed the self-fertilised in average height, so that this is not one of the exceptions here to be considered.  In two other cases the crossed equalled the self-fertilised in height within five per cent; and in the fourth case the self-fertilised exceeded the crossed by above this limit.  We have seen in Table 7/C that the whole advantage of a cross by a fresh stock is confined to fertility, and so it was with the intercrossed plants of the same stock compared with the self-fertilised, for the former were in fertility to the latter as 100 to 89.  The intercrossed plants thus have at least one important advantage over the self-fertilised.  Moreover, the flowers on the parent-plants when fertilised with pollen from another individual of the same stock yield far more seeds than when self-fertilised; the flowers in this latter case being often quite sterile.  We may therefore conclude that a cross does some good, though it does not give to the crossed seedlings increased powers of growth.

7.  Viscaria oculata.

The average height of the fifteen intercrossed plants to that of the fifteen self-fertilised plants was only as 100 to 97; but the former produced many more capsules than the latter, in the ratio of 100 to 77.  Moreover, the flowers on the parent-plants which were crossed and self-fertilised, yielded seeds on one occasion in the proportion of 100 to 38, and on a second occasion in the proportion of 100 to 58.  So that there can be no doubt about the beneficial effects of a cross, although the mean height of the crossed plants was only three per cent above that of the self-fertilised plants.