at a distance was placed on both stigmas; and as the plant was left uncovered, pollen from other flowers on the Ragged Jack would certainly have been left by the bees during the next two or three days on the same two stigmas.  Under these circumstances it seemed very unlikely that the pollen of the Barnes cabbage would produce any effect; but three out of the fifteen plants raised from the two capsules thus produced were plainly mongrelised:  and I have no doubt that the twelve other plants were affected, for they grew much more vigorously than the self-fertilised seedlings from the Ragged Jack planted at the same time and under the same conditions.  Secondly, I placed on several stigmas of a long-styled cowslip (Primula veris) plenty of pollen from the same plant, and after twenty-four hours added some from a short-styled dark-red Polyanthus, which is a variety of the cowslip.  From the flowers thus treated thirty seedlings were raised, and all these without exception bore reddish flowers; so that the effect of the plant’s own pollen, though placed on the stigmas twenty-four hours previously, was quite destroyed by that of the red variety.  It should, however, be observed that these plants are dimorphic, and that the second union was a legitimate one, whilst the first was illegitimate; but flowers illegitimately fertilised with their own pollen yield a moderately fair supply of seeds.

We have hitherto considered only the prepotent fertilising power of pollen from a distinct variety over a plants’ own pollen,—­both kinds of pollen being placed on the same stigma.  It is a much more remarkable fact that pollen from another individual of the same variety is prepotent over a plant’s own pollen, as shown by the superiority of the seedlings raised from a cross of this kind over seedlings from self-fertilised flowers.  Thus in Tables 7/A, B, and C, there are at least fifteen species which are self-fertile when insects are excluded; and this implies that their stigmas must receive their own pollen; nevertheless, most of the seedlings which were raised by fertilising the non-castrated flowers of these fifteen species with pollen from another plant were greatly superior, in height, weight, and fertility, to the self-fertilised offspring. (10/40.  These fifteen species consist of Brassica oleracea, Reseda odorata and lutea, Limnanthes douglasii, Papaver vagum, Viscaria oculata, Beta vulgaris, Lupinus luteus, Ipomoea purpurea, Mimulus luteus, Calceolaria, Verbascum thapsus, Vandellia nummularifolia, Lactuca sativa, and Zea mays.) For instance, with Ipomoea purpurea every single intercrossed plant exceeded in height its self-fertilised opponent until the sixth generation; and so it was with Mimulus luteus until the fourth generation.  Out of six pairs of crossed and self-fertilised cabbages, every one of the former was much heavier than the latter.  With Papaver vagum, out of fifteen pairs, all but two of the crossed plants were taller than their self-fertilised opponents.