Passing next to cases in which the stamens and pistils of the same flower come to maturity at different times, so as to make cross-breeding a necessity, we may mention first some plants in which the pollen ripens before the stigma is ready to receive it. We have such a condition of things in the _willow-herb_, or _epilobium tribe_. The pretty pink blossoms of a large variety of this genus are to be found, in summer, along the banks of brooks and running ditches. We will confine our remarks to the species distinguished by its narrow leaves, and hence named _angustifolium_. When the flower has fully opened, the eight stamens spread out, and their anthers shed the pollen. Bees visit the blossoms, and getting dusted with the grains, carry these away to other flowers of the same kind. And here, in passing, we may recall the fact of bees keeping to one species of plant during the whole of any one journey from the hive. The importance of this can be now better appreciated, when its influence on the fructification of blossoms is observed. But to return, the pistil of the willow-herb remains, till the stamens have withered, curved round out of the way, and unable to receive any of their pollen. Then, after they are dead, it comes into such a position that it can take what pollen may be brought to it from younger flowers. For the conveyance of this it is dependent chiefly on bees, who do not fail to carry enough for the required purpose. In this way each blossom, by the agency of these insects, both gives and gets what is necessary for the continued life of the species; and without these unconsciously conferred benefits from insect life, no seeds of this kind of _epilobium_ would mature. Another instance, equally interesting, is seen in the well-known _cineraria_ tribe. The plants of this genus belong to the _composite_ order, in which what is usually called the blossom, consists of many flowers, grouped together on one head. In the example before us, there are nearly 200 thus aggregated. These florets separately open at different times, those of the outer circles coming before those nearer the centre. The pollen-tube of each is formed by five anthers, fastened together at their edges, and discharging their pollen into the space between them. At the lower part of this inclosure the pistil is growing, but is not in a condition to receive usefully the fertilising powder. It, however, as it advances, sweeps out, and carries up with it, the pollen-grains, so that they may be conveyed to other florets of the same or other blossoms, to effect their vitalising work. At length the pistil, with its brush on its summit, comes into view, but, even yet, is not sufficiently developed for fertilisation. In due course, however, the upper end splits, and exposes the surface of the stigma ready for the pollen, which must be brought from some other floret, and probably from some other blossom. Thus cross-breeding is effectually secured.