their weight, except in one case, and here the ratio is as high as 100 to 67. The results thus deduced from the weights of the plants confirm in a striking manner the former evidence of the beneficial effects of a cross between two plants of the same stock; and in the few cases in which plants derived from a cross with a fresh stock were weighed, the results are similar or even more striking. CHAPTER VIII. DIFFERENCE BETWEEN CROSSED AND SELF-FERTILISED PLANTS IN CONSTITUTIONAL VIGOUR AND IN OTHER RESPECTS. Greater constitutional vigour of crossed plants. The effects of great crowding. Competition with other kinds of plants. Self-fertilised plants more liable to premature death. Crossed plants generally flower before the self-fertilised. Negative effects of intercrossing flowers on the same plant. Cases described. Transmission of the good effects of a cross to later generations. Effects of crossing plants of closely related parentage. Uniform colour of the flowers on plants self-fertilised during several generations and cultivated under similar conditions. GREATER CONSTITUTIONAL VIGOUR OF CROSSED PLANTS. As in almost all my experiments an equal number of crossed and self-fertilised seeds, or more commonly seedlings just beginning to sprout, were planted on the opposite sides of the same pots, they had to compete with one another; and the greater height, weight, and fertility of the crossed plants may be attributed to their possessing greater innate constitutional vigour. Generally the plants of the two lots whilst very young were of equal height; but afterwards the crossed gained insensibly on their opponents, and this shows that they possessed some inherent superiority, though not displayed at a very early period in life. There were, however, some conspicuous exceptions to the rule of the two lots being at first equal in height; thus the crossed seedlings of the broom (Sarothamnus scoparius) when under three inches in height were more than twice as tall as the self-fertilised plants.