which were raised at the same time close alongside.  But as I did not measure their actual height I cannot give the exact ratio, but it must have been at least as 100 to 75.  A similar trial was subsequently made with two other peas from a different cross, and the result was nearly the same.  For instance, a crossed seedling between the Maple and Purple-podded pea was planted in poor soil and grew to the extraordinary height of 116 inches; whereas the tallest plant of either parent variety, namely, a Purple-podded pea, was only 70 inches in height; or as 100 to 60.

Sarothamnus scoparius.

Bees incessantly visit the flowers of the common Broom, and these are adapted by a curious mechanism for cross-fertilisation.  When a bee alights on the wing-petals of a young flower, the keel is slightly opened and the short stamens spring out, which rub their pollen against the abdomen of the bee.  If a rather older flower is visited for the first time (or if the bee exerts great force on a younger flower), the keel opens along its whole length, and the longer as well as the shorter stamens, together with the much elongated curved pistil, spring forth with violence.  The flattened, spoon-like extremity of the pistil rests for a time on the back of the bee, and leaves on it the load of pollen with which it is charged.  As soon as the bee flies away, the pistil instantly curls round, so that the stigmatic surface is now upturned and occupies a position, in which it would be rubbed against the abdomen of another bee visiting the same flower.  Thus, when the pistil first escapes from the keel, the stigma is rubbed against the back of the bee, dusted with pollen from the longer stamens, either of the same or another flower; and afterwards against the lower surface of the bee dusted with pollen from the shorter stamens, which is often shed a day or two before that from the longer stamens. (5/16.  These observations have been quoted in an abbreviated form by the Reverend G. Henslow, in the ‘Journal of Linnean Society Botany’ volume 9 1866 page 358.  Hermann Muller has since published a full and excellent account of the flower in his ‘Befruchtung’ etc. page 240.) By this mechanism cross-fertilisation is rendered almost inevitable, and we shall immediately see that pollen from a distinct plant is more effective than that from the same flower.  I need only add that, according to H. Muller, the flowers do not secrete nectar, and he thinks that bees insert their proboscides only in the hope of finding nectar; but they act in this manner so frequently and for so long a time that I cannot avoid the belief that they obtain something palatable within the flowers.