Firstly, seedlings were raised from self-fertilised seeds produced under a net by crossed and self-fertilised plants of Nemophila insignis; and the latter were to the former in height as 133 to 100.  But these seedlings became very unhealthy early in life, and grew so unequally that some of them in both lots were five times as tall as the others.  Therefore this experiment was quite worthless; but I have felt bound to give it, as opposed to my general conclusion.  I should state that in this and the two following trials, both sets of plants were grown on the opposite sides of the same pots, and treated in all respects alike.  The details of the experiments may be found under the head of each species.

Secondly, a crossed and a self-fertilised plant of Heartsease (Viola tricolor) grew near together in the open ground and near to other plants of heartsease; and as both produced an abundance of very fine capsules, the flowers on both were certainly cross-fertilised by insects.  Seeds were collected from both plants, and seedlings raised from them.  Those from the crossed plants flowered in all three pots before those from the self-fertilised plants; and when fully grown the former were to the latter in height as 100 to 82.  As both sets of plants were the product of cross-fertilisation, the difference in their growth and period of flowering was clearly due to their parents having been of crossed and self-fertilised parentage; and it is equally clear that they transmitted different constitutional powers to their offspring, the grandchildren of the plants which were originally crossed and self-fertilised.

Thirdly, the Sweet Pea (Lathyrus odoratus) habitually fertilises itself in this country.  As I possessed plants, the parents and grandparents of which had been artificially crossed and other plants descended from the same parents which had been self-fertilised for many previous generations, these two lots of plants were allowed to fertilise themselves under a net, and their self-fertilised seeds saved.  The seedlings thus raised were grown in competition with each other in the usual manner, and differed in their powers of growth.  Those from the self-fertilised plants which had been crossed during the two previous generations were to those from the plants self-fertilised during many previous generations in height as 100 to 90.  These two lots of seeds were likewise tried by being sown under very unfavourable conditions in poor exhausted soil, and the plants whose grandparents and great-grandparents had been crossed showed in an unmistakable manner their superior constitutional vigour.  In this case, as in that of the heartsease, there could be no doubt that the advantage derived from a cross between two plants was not confined to the offspring of the first generation.  That constitutional vigour due to cross-parentage is transmitted for many generations may also be inferred as highly probable, from some of Andrew Knight’s varieties of the common pea,